OUI / DUI Drunk Driving Defense Lawyer in Greater Boston

Massachusetts prosecutes drunk driving under G.L. c. 90, § 24, the operating under the influence statute. The charge is commonly called OUI. When police make an arrest, the arrest is ordinarily followed by an application for a criminal complaint in the District Court or Boston Municipal Court. The arrest itself does not suspend the driver’s license.

In an alcohol OUI case, a refusal of a chemical test for alcohol or a qualifying blood alcohol result may cause a separate Registry action. A later court disposition may cause another license consequence. Attorney Serpa has tried these cases in the Greater Boston courts since 1995.

Serpa Law Office addresses the Commonwealth’s evidence, breath testing, field sobriety testing, the consequences of a conviction or refusal, and the defense of an OUI charge.

The statute states a single offense that the Commonwealth may prove in either of two ways. Under G.L. c. 90, § 24(1)(a)(1), a person is guilty who operates a motor vehicle, on a way or in a place where the public has access, either while under the influence of intoxicating liquor or with a blood alcohol percentage of .08 or greater. The first way is the impairment theory.

The second is the per se theory. The Commonwealth need not prove impaired driving under that theory; it must prove only the qualifying test result. A judge following Massachusetts District Court Criminal Model Jury Instruction 5.310, “Operating Under the Influence of Intoxicating Liquor” (rev. Mar. 2023), instructs the jury that impairment and the per se theory are two ways of committing one offense.

The Elements the Commonwealth Must Prove

The Commonwealth must prove three elements beyond a reasonable doubt: operation, a public way, and either impairment or a blood alcohol level of .08 or greater. Each element must be proved, and each is open to challenge.

Operation is defined broadly. Under the governing definition, a person operates when, while in the vehicle, the person intentionally performs an act or uses a mechanical or electrical component that, alone or in sequence, will set the vehicle’s motive power in motion. Commonwealth v. Uski, 263 Mass. 22, 24 (1928); Commonwealth v. Wurtzberger, 496 Mass. 203, 206 (2025). The vehicle need not move, and the engine need not be running.

In Wurtzberger, the evidence showed that the defendant was in the driver’s seat with the ignition key turned far enough to power the radio while the engine remained off. The Supreme Judicial Court held that the evidence permitted a finding of operation because turning the key was an intentional act in the sequence that could set the vehicle’s motive power in motion. A person’s private intent merely to use the vehicle as a stationary place does not change that analysis.

Operation is often the contested element when the police find a driver parked, stopped on the shoulder, or asleep behind the wheel, and the defense examines whether the evidence shows an intentional act to engage the vehicle and whether another person may have driven.

The public way element requires that the operation occur, in the words of the statute, upon a way or in a place to which the public has a right of access, or to which members of the public have access as invitees or licensees. G.L. c. 90, § 24(1)(a)(1). The word “way” is defined in G.L. c. 90, § 1.

G.L. c. 90, § 24 limits the public-access element to a place that the public may reach by motor vehicle. The status of the place, not the status of the driver, controls. Commonwealth v. George, 406 Mass. 635 (1990). Courts evaluate objective indicia of public access, including paving, curbing, street lights, traffic signals, and abutting homes or businesses. Commonwealth v. Smithson, 41 Mass. App. Ct. 545 (1996).

Whether a place is one of public access is a legal conclusion that an appellate court reviews on the objective circumstances. Commonwealth v. Virgilio, 79 Mass. App. Ct. 570 (2011). A parcel posted against trespassers and used without the owner’s permission is not such a place. Commonwealth v. Callahan, 405 Mass. 200 (1989). A private lot behind a locked gate is a different matter, and the element is not automatic.

The third element is proved in one of two ways. On the impairment theory, the Commonwealth relies on observational evidence that the person’s consumption of alcohol impaired the ability to operate a motor vehicle safely. Commonwealth v. Connolly, 394 Mass. 169 (1985). It does not have to prove erratic driving, only a diminished capacity to drive safely.

On the per se theory, the Commonwealth relies on a test result at or above .08 percent, whether from a certified breath test or from a hospital record of the blood alcohol level, and it does not have to prove impairment at all. Commonwealth v. Colturi, 448 Mass. 809 (2007). The .08 percent criminal threshold applies regardless of age. For a person under 21, a result of .02 or greater instead triggers separate administrative license provisions under G.L. c. 90, § 24(1)(f)(2), and § 24P.

The Breath Test

The breath test used in Massachusetts is the Draeger Alcotest 9510. For a breath result to be admissible, the test must be administered by a certified breath test operator on an infrared breath-testing device certified under the governing regulations, using approved methods. Breath test operator certification is valid for three years under 501 CMR 2.07(3); the device certification is valid for one year under 501 CMR 2.06. G.L. c. 90, § 24K.

The regulations require a fixed sequence: an adequate breath sample, a control-standard analysis, and a second adequate breath sample. The Office of Alcohol Testing certifies the devices and sets the standards under 501 CMR 2.00. Each device must be certified, and a certification is valid for one year. The control-standard result in a valid test must read between 0.074 and 0.086.

A missing annual certification, a bad calibration record, or a broken sequence is a foundation problem, and it can keep the result out. The firm explains the instrument and the science in detail on its pages on the breath test and the Alcotest 9510 and on defending the breath test.

In the consolidated Ananias litigation, the District Court established a historical presumption of exclusion for results from Alcotest 9510 machines last calibrated and certified before April 18, 2019, after the Office of Alcohol Testing withheld failed calibration worksheets. Limited case-specific exceptions applied to motor vehicle homicide, OUI serious bodily injury, and fifth-or-subsequent-offense prosecutions.

Breath results are admissible again from Alcotest 9510 machines calibrated and certified on or after April 18, 2019, subject to a case-by-case challenge to the reliability of the particular machine. In an individual case, admissibility still depends on the Commonwealth’s producing the certification and calibration records applicable to the machine when the test was administered.

The Breath Test Refusal

A driver may refuse the breathalyzer, and refusal causes an immediate Registry suspension that is separate from any suspension imposed through a court disposition. Under G.L. c. 90, § 24(1)(f)(1), the period is 180 days for a driver age 21 or older with no qualifying prior offense, three years for a driver under 21 or a driver with one qualifying prior offense, five years with two qualifying prior offenses, and lifetime with three or more qualifying prior offenses. Three prior offenses means the current arrest would be treated as a potential fourth offense. For this rule, a qualifying prior offense can include an OUI conviction, an admission to sufficient facts followed by a continuance without a finding, or assignment to a qualifying alcohol or controlled-substance education, treatment, or rehabilitation program; a qualifying out-of-state disposition may also count.

Separate 10-year and lifetime refusal provisions apply after specified prior serious-injury, motor vehicle homicide, or manslaughter convictions. These are Registry consequences, and the refusal period does not depend on a conviction in the new criminal case.

A refusal is not admissible against the driver at trial. The statute provides that evidence of a refusal is not admissible in a civil or criminal proceeding. G.L. c. 90, § 24(1)(e). The rule also has a constitutional basis. A statute that made breath test refusal admissible in a criminal case would violate article 12 of the Massachusetts Declaration of Rights, because a refusal is testimonial.

Evidence that a driver refused field sobriety tests is likewise inadmissible because the refusal is testimonial, even though performing the tests produces physical evidence. Commonwealth v. McGrail, 419 Mass. 774, 779-780 (1995).

Commonwealth v. Blais, 428 Mass. 294, 299 & n.3 (1998), later disapproved McGrail to the extent it suggested that a driver has no legal obligation to perform the tests. Blais held that police may request field sobriety tests during a lawful stop based on reasonable suspicion of OUI and need not advise the driver that the tests may be refused. The Article 12 protection concerns the admissibility of the refusal, not a general privilege to withhold physical evidence.

The Field Sobriety Tests

The standardized field sobriety tests are the horizontal gaze nystagmus test, the walk and turn, and the one leg stand. The National Highway Traffic Safety Administration designed them to classify a driver’s blood alcohol at or above .08, at the accuracy rates the agency claims for them. The walk and turn is scored on two or more of eight clues, the one leg stand on two or more of four clues, and the horizontal gaze nystagmus test on four or more of six clues.

The manual does not contain a failing score. The word “failed” is courtroom shorthand, not a result the test produces, and an officer should not testify that a driver passed or failed.

The horizontal gaze nystagmus test is different from the other two. It rests on a scientific proposition about involuntary eye movement, so it requires expert testimony and a scientific foundation before a jury may hear it. Commonwealth v. Sands, 424 Mass. 184 (1997). The walk and turn and the one leg stand are within a juror’s common experience and do not require an expert.

An officer who watched the driver may give an opinion on the driver’s level of sobriety, but may not give an opinion on the ultimate question, whether the driver was under the influence or whether alcohol impaired the ability to operate. Commonwealth v. Canty, 466 Mass. 535 (2013). The firm cross-examines the officer on the instructions given, the conditions of the roadside, and the scoring on its page on cross-examining the field sobriety opinion, and it explains the tests and the science on its field sobriety test defense page.

Operating Under the Influence of Drugs

The field sobriety tests were developed for alcohol, and there is no scientific consensus that performance correlates with marijuana use or impairment. In a marijuana case, the officer may describe performance only as roadside assessments of balance, coordination, mental acuity, and other driving-related skills. The officer may not testify that the driver passed or failed, that the assessments established marijuana impairment, or offer a lay opinion that the driver was intoxicated by marijuana.

The jury may consider those observations with the other evidence, but roadside-assessment performance alone cannot support a conviction. Commonwealth v. Gerhardt, 477 Mass. 775, 776-777, 783-785 (2017). The firm addresses the remaining evidence issues on its OUI drugs and marijuana defense page.

The Criminal Case and Registry License Actions

Different rules apply to the criminal prosecution and a Registry license action. The criminal case proceeds in the District Court or Boston Municipal Court, where the Commonwealth must prove the charged offense. In an alcohol OUI case, refusal of a chemical test for alcohol or a qualifying blood alcohol result may cause a Registry suspension before disposition. A later court disposition may cause an additional license consequence. A refusal suspension becomes effective when the driver receives the officer’s notice.

An immediate threat suspension under M.G.L. c. 90, § 22(a) is separate from all three. Police may ask the RMV to suspend a person’s license immediately and indefinitely based on the reported driving conduct, even without an arrest, refusal of the breathalyzer, qualifying test result, guilty plea, or conviction. This matters when the OUI investigation leads to a summons: the chemical-test suspensions ordinarily do not arise without an arrest, but an immediate threat request can still be submitted. The Massachusetts immediate threat license suspension guide explains the police request, RMV hearing, records, pending criminal case, and appeals. The immediate threat FAQs provide concise answers.

A driver who submits to the breath test and produces a result of .08 or greater ordinarily has the license taken by police. The suspension lasts until disposition of the offense, but no more than 30 days. G.L. c. 90, § 24(1)(f).

A suspension based on a court disposition is separate. Attorney Serpa handles the criminal case and advises on the Registry process, but he does not appear with clients at the Registry. The firm addresses the principal refusal and result-based rules in its Massachusetts OUI FAQs and limited-license eligibility in its hardship-license guide.

Penalties by Offense Number

A first offense under G.L. c. 90, § 24(1)(a)(1) is punishable by a fine of not less than $500 and not more than $5,000, by incarceration of up to two and one half years in a house of correction, or by both, along with a mandatory $250 head injury assessment and a $50 assessment.

For an OUI conviction revocation imposed without a disposition under G.L. c. 90, § 24D, the one-year revocation applies when the person has no qualifying prior. The first hardship-hearing date is three months after conviction. Section 24 provides a second hearing date after six months.

At three months, Section 24 permits a request for a license for employment or education. At six months, it permits a request for a limited license on general hardship grounds. Under the current Registry of Motor Vehicles criteria, medical treatment or another supported purpose can support the later request. The applicant must document the need, explain why public transportation cannot meet it, and show that the causes of the current and prior violations have been addressed or brought under control. Any approved license uses the same fixed 12-hour period each day. Approval remains discretionary.

Most first offenders resolve the case under the alternative disposition in G.L. c. 90, § 24D. A person is eligible as a true first offender, and once in a lifetime a person is eligible whose single prior like offense was disposed of by a court of the Commonwealth or any other jurisdiction 10 years or more before the date of the new offense.

A § 24D disposition places an eligible person on probation for up to two years and requires participation in the driver-alcohol education or treatment program specified by the statute. The license suspension is ordinarily 45 to 90 days, but it is 210 days if the person was under 21 when the offense was committed.

Upon entering the required program, the person may immediately apply to the Registry for consideration of a hardship license; issuance is discretionary. An ignition interlock device may be required if the blood alcohol percentage was .15 or greater. Section 24D is unavailable if the incident caused serious personal injury or death.

Under the ordinary second-offense sentencing provision, a second offense carries both a fine of not less than $600 and not more than $10,000 and imprisonment for not less than 60 days and not more than two and one-half years in a house of correction. The sentence may not be reduced below 30 days, and at least 30 days must be served. G.L. c. 90, § 24(1)(a)(1).

As an alternative to that jail time, a second offender who consents may instead be placed on probation for two years with a mandatory 14 day residential alcohol treatment program, on the judge’s written findings. G.L. c. 90, § 24(1)(a)(4). A second offense ordinarily revokes the license for two years.

When the only prior is 10 years or more old, the person may receive the first-offender type disposition under G.L. c. 90, § 24D. The resulting license suspension is ordinarily 45 to 90 days rather than two years, but it is 210 days if the person was under 21 when the new offense was committed. Commonwealth v. Cahill, 442 Mass. 127 (2004). The firm explains this limited second disposition on its Cahill second offense page.

The third and later offenses are felonies. A third offense is punishable by a fine of not less than $1,000 and not more than $15,000 and by imprisonment for two and one-half to five years in state prison or for 180 days to two and one-half years in a house of correction. The sentence may not be reduced below 150 days, and at least 150 days must be served.

A third-offense conviction revokes the license for eight years. After two years, the person may request a license for employment or education. After four years, the person may request a limited license on general hardship grounds. Either request remains subject to the Registrar’s discretion.

A fourth offense is punishable by a fine of not less than $1,500 and not more than $25,000 and by two and one half to five years in state prison or two to two and one half years in a house of correction, of which one year must be served. A conviction revokes the license for ten years. After five years, the person may request a license for employment or education. After eight years, the person may request a limited license on general hardship grounds. Either request remains subject to the Registrar’s discretion.

A fifth offense is punishable by a fine of not less than $2,000 and not more than $50,000 and by two and one half to five years in state prison or two and one half years in a house of correction, of which two years must be served. A conviction revokes the license for life, and the ordinary hardship procedure provides no hearing. Massachusetts law requires the sentencing calculation to include qualifying prior offenses over the driver’s lifetime, subject to the narrow additional Section 24D disposition described above.

Melanie’s Law requires an ignition interlock device for repeat offenders. G.L. c. 90, § 24½. A person whose license is suspended for an OUI conviction or program assignment, in the Commonwealth or any other jurisdiction, and who has a prior such conviction or assignment, cannot obtain a new or restored license unless a certified device is installed on every vehicle the person owns, leases, and operates, and the device must remain for two years.

For a second-offense revocation without a Section 24D disposition, the person may request a license for employment or education after one year. After 18 months, the person may request a limited license on general hardship grounds. Either request remains subject to the Registrar’s discretion. An ignition interlock device is mandatory for any approved hardship license.

A person receiving the once-in-a-lifetime Section 24D disposition described above may instead apply for hardship consideration immediately after entering the program. Because the person has a qualifying prior, the repeat-offender ignition-interlock requirement still applies. Operating in violation of an ignition-interlock restriction is a separate crime under G.L. c. 90, § 24S.

A prior offense can come from another state. Under G.L. c. 90, § 24, a prior offense includes a conviction, or a court ordered program assignment, entered by a court of the Commonwealth or any other jurisdiction for a like violation. An out-of-state OUI conviction counts as a prior offense.

An out-of-state action that was purely administrative, such as an implied consent refusal suspension entered by a motor vehicle agency with no court disposition, is neither a conviction nor a court assignment, and it does not count as a prior offense. Similarly, a Massachusetts OUI conviction or program can count as a prior offense if a driver is charged with a subsequent offense in another state.

Serious Injury, Death, and a Child in the Vehicle

G.L. c. 90, § 24L contains two OUI serious-bodily-injury offenses. Subsection (1) requires proof that the defendant operated under the influence or at the charged blood alcohol percentage, operated negligently or recklessly, and caused serious bodily injury. It is a felony punishable by a fine of not more than $5,000 and either two and one-half to ten years in state prison or six months to two and one-half years in a house of correction. At least six months must be served.

Subsection (2) requires proof that the OUI operation caused serious bodily injury, but it does not require separate negligent or reckless operation. It is punishable by up to two and one-half years in a house of correction, a fine of at least $3,000, or both. For both offenses, serious bodily injury means an injury that creates a substantial risk of death or causes total disability, loss, or substantial impairment of a bodily function for a substantial period. A conviction causes a two-year license revocation.

G.L. c. 90, § 24G(a) applies when OUI operation, together with negligent or reckless operation, causes a death. It is punishable by a fine of not more than $5,000 and either two and one-half to fifteen years in state prison or one to two and one-half years in a house of correction. At least one year must be served.

Section 24G(b) also contains an OUI motor vehicle homicide offense. The Commonwealth must prove that operation under the influence or at .08 or greater caused the death, but it need not prove separate negligent or reckless operation. The offense is punishable by a fine of $300 to $3,000, incarceration for 30 days to two and one-half years, or both. A fine without incarceration is therefore authorized.

A conviction for homicide by motor vehicle under § 24G ordinarily revokes the license for 15 years on a first offense and for life on a subsequent offense. Section 24R can require lifetime revocation based on qualifying prior convictions.

G.L. c. 90, § 24V applies when a child who is 14 years old or younger is in the vehicle during a listed OUI offense. It does not require proof that the operation caused an injury. A first offense is punishable by a fine of $1,000 to $5,000, 90 days to two and one-half years in a house of correction, and a one-year license suspension. The sentence is consecutive to the sentence for the underlying offense.

The Commonwealth need not prove the same elements for each charge. The OUI-causing-serious-bodily-injury offenses under Section 24L and the homicide-by-motor-vehicle offenses under Section 24G require causation. The felony provisions in Sections 24L(1) and 24G(a) also require negligent or reckless operation, while the child-endangerment offense under Section 24V requires the child’s presence rather than causation. The firm addresses the related charges on its page about motor vehicle homicide and operating to endanger.

The Defense of a Massachusetts OUI Case

A strong defense begins at the stop. The police need a lawful reason to stop the vehicle, a lawful basis for an exit order, and a lawful basis for each step that follows. The defense examines the reason for the stop, the observations the officer recorded, the instructions given before the field sobriety tests, the conditions of the roadside, and the foundation for the breath test.

Where the stop or a later step was unlawful, a motion to suppress can lead to dismissal, because a judge can suppress the officer’s observations and any other evidence the police obtained after a bad motor vehicle stop. A motion for a required finding of not guilty can end the case before jury deliberations if the Commonwealth has not proven one or more of the elements discussed above.

At trial, Attorney Serpa cross-examines the officer about the observations, field-test scoring, and breath-test result, if applicable. He prepares the examination from the case-specific evidence rather than a fixed script. The firm addresses the governing cross-examination principles on its cross-examination page.

An OUI complaint often includes additional offenses, usually operating to endanger, negligent or reckless operation, or operating after a suspension. Many OUI arrests also begin at a sobriety checkpoint, which has its own rules.

Who Attorney Serpa Represents

Attorney Serpa represents people charged with operating under the influence across Greater Boston, from a first offense to a subsequent offense, and in cases that involve a breath test, a refusal, drugs, or a serious injury. The office also represents those who face added consequences from an OUI, including college and university students, licensed professionals, and non-citizens.

The office answers questions about the criminal case and the Registry consequences together, so a client understands both from the start. Contact Serpa Law Office at 617.936.0201 for a free, confidential consultation. Serpa Law Office has offices at 20 Park Plaza, Suite 400A, in Boston and 500 Victory Road, Suite 400A, in Quincy.

Massachusetts Courts Where Attorney Serpa Tries These Cases

Attorney Serpa tries OUI cases in the Boston Municipal Court and in the District Courts of Greater Boston, including the courts in Quincy, Dedham, Cambridge, Somerville, Malden, Framingham, and the surrounding communities. He has tried cases in these buildings since 1995. The firm keeps a guide to the Massachusetts District Courts, and Attorney Serpa’s background is on his profile.

Related Serpa Law Office Resources

Serpa Law Office organizes its OUI and related motor vehicle pages in the Massachusetts OUI and motor vehicle defense hub.

Last Reviewed: August 2026