DUI / DWI charges explained

What the prosecution must prove

• Actual physical control or operation of a motor vehicle — prosecutors must show the defendant was driving or in control of the vehicle, not merely a passenger.
• The driving or control occurred on a public road or, in many states, on any location accessible to the public such as a parking lot.
• The defendant was under the influence of alcohol, a controlled substance, or another impairing substance to a degree that affected their ability to drive safely, OR their BAC tested at or above the applicable per se legal limit (typically 0.08% for adults).
• In per se cases, a valid chemical test — breath, blood, or urine — was administered within the time window required by state law and the result met or exceeded the statutory threshold.
• For drug-impaired driving charges, many states require additional evidence such as a Drug Recognition Expert evaluation, field sobriety test results, or a confirmed positive chemical test for a specific impairing substance.

Typical penalties across the U.S.

Common defenses

• Lack of reasonable suspicion or probable cause for the traffic stop — if law enforcement stopped the vehicle without a lawful basis, evidence gathered afterward may be suppressed under the Fourth Amendment.
• Improper administration of field sobriety tests — standardized tests such as the Horizontal Gaze Nystagmus, Walk-and-Turn, and One-Leg Stand must follow specific protocols; deviations can undermine their reliability.
• Breathalyzer calibration and maintenance issues — breath testing devices require regular calibration and certified maintenance; failure to meet those requirements can make the BAC result inadmissible or unreliable.
• Rising blood alcohol defense — alcohol continues to absorb into the bloodstream after drinking stops, so a defendant's BAC at the time of driving may have been below the legal limit even if it registered at or above 0.08% when tested later.
• Medical conditions or environmental factors — certain medical conditions such as GERD, diabetes, or the presence of mouth alcohol can skew breath test results; similarly, some medical conditions can mimic signs of intoxication such as slurred speech or unsteady gait.
• Chain of custody and lab errors in blood tests — blood samples must be properly collected, stored, and analyzed; breaks in the chain of custody or laboratory errors can challenge the accuracy and admissibility of results.

Consequences beyond the sentence

• Driver's license suspension or revocation through a separate administrative proceeding handled by the state DMV, which is independent of the criminal case and can take effect quickly after arrest.
• Dramatically increased auto insurance premiums or outright policy cancellation; an SR-22 certificate of financial responsibility is typically required for reinstatement, adding ongoing costs for years.
• Employment consequences including loss of a commercial driver's license (CDL), disqualification from jobs requiring driving, security clearances, or professional licenses in fields such as law, medicine, nursing, or education.
• Immigration consequences for non-citizens, including potential grounds for deportation or inadmissibility depending on the nature of the conviction and the individual's immigration status.
• A permanent criminal record that appears on background checks, affecting housing applications, firearm rights in some states, and eligibility for federal student loans or public benefits if a felony conviction results.

What to do right now

• Request and write down every detail you remember about the stop, arrest, and testing as soon as possible — including the officer's name, badge number, the sequence of events, weather, road conditions, and anything said on both sides.
• Contact a licensed DUI defense attorney in the state where you were charged before speaking to anyone else about the incident; invoke your right to counsel and remain silent regarding the facts of the case.
• Note the deadline for requesting a DMV administrative hearing to contest your license suspension — this window is often only 5–10 days from arrest in many states and missing it results in automatic suspension.
• Gather all documents provided at arrest, including the citation, any notice of suspension, and the police report if available, and give copies to your attorney rather than posting or discussing details publicly.
• Follow all conditions of your release, appear at every scheduled court date, and comply with any court-ordered restrictions such as refraining from alcohol consumption or installing an ignition interlock device if ordered as a pre-trial condition.

Questions to ask a defense lawyer

• What are the specific strengths and weaknesses of the evidence against me, including the legality of the traffic stop and the reliability of any chemical test results?
• Is there a viable motion to suppress evidence, and if so, how likely is it to succeed and what would suppression mean for my case?
• What are the realistic outcomes — dismissal, reduction to a lesser charge like reckless driving, a plea agreement, or trial — and what do you recommend given the facts?
• How will you handle the DMV administrative hearing, and what strategy do you recommend to protect or restore my driving privileges as quickly as possible?
• What will your total fees be, what does that cover, and are there any circumstances in which costs could increase significantly as the case proceeds?