Drunk driving laws in the United States were first enacted in 1906, when New Jersey passed the country’s first statute specifically criminalizing operating an automobile while intoxicated. New York followed in 1910, and other states adopted similar bans over the next two decades. Everything since has been refinement: adding chemical tests, lowering the legal blood alcohol limit, raising penalties, and using federal highway dollars to pull every state into line.
The 1906 Starting Point
Before cars became common, people who caused harm while intoxicated on horseback or in a carriage were charged under general laws like public drunkenness or reckless conduct. Those statutes were not built around vehicles, and enforcement was entirely subjective.
New Jersey’s 1906 law changed that by targeting the automobile directly. But the early statutes shared a serious weakness: none of them defined what “intoxicated” meant. A police officer had to rely on the smell of alcohol, bloodshot eyes, slurred speech, or whether a driver could walk a straight line. Two officers watching the same driver could easily reach opposite conclusions, and convictions were inconsistent.
Chemical Testing Gives the Laws Teeth
The search for an objective measurement produced two landmark inventions. In 1931, Dr. Rolla N. Harger, a biochemist at Indiana University, created the Drunkometer, a device that estimated blood alcohol content from a breath sample collected in a balloon. Harger patented it in 1936, just as Prohibition was ending.
In 1938, a joint committee of the American Medical Association and the National Safety Council issued the first scientific guidelines for legal intoxication. The committee set 0.15% BAC as the threshold at which any person had measurably lost clarity and self-control. That number became the basis for the Chemical Tests Section of the Uniform Vehicle Code and shaped state laws for decades.
In 1954, Robert Borkenstein, a former Indiana state police captain, invented the Breathalyzer. It was smaller, more reliable, and easier to use than the Drunkometer, and it made roadside testing practical. For the first time, prosecutors had a number to put in front of a jury instead of an officer’s impression.
Implied Consent and Per Se Laws
Chemical testing only works if drivers actually submit to it. In the 1950s, states began passing implied consent laws, which established that anyone operating a vehicle on public roads has already agreed to submit to a breath, blood, or urine test if lawfully arrested on suspicion of impaired driving. Refusing triggers automatic penalties, typically a license suspension, even without a DUI conviction. New York was among the earliest states to adopt this approach, and by the 1970s implied consent was nearly universal.
Per se laws followed. Under traditional DUI statutes, prosecutors had to prove a driver was actually impaired. Per se laws eliminated that requirement: if your BAC was at or above the legal limit, you were guilty regardless of how well you appeared to drive. States began adopting per se laws in the 1960s and 1970s, initially at the 0.15% threshold from 1938, and later at 0.10%.
The 1980s: MADD and Federal Leverage
The 1980s transformed American drunk driving policy more than any other decade. On May 3, 1980, 13-year-old Cari Lightner was killed by a driver with four prior DUI arrests who had been released from jail two days earlier. Her mother, Candace Lightner, founded Mothers Against Drunk Driving that same year. MADD pushed state legislatures and Congress to treat drunk driving as a serious crime rather than a minor traffic offense. Penalties climbed, courts began ordering alcohol treatment, and the political cost of opposing tougher laws grew steep.
The federal government stepped in with the National Minimum Drinking Age Act of 1984. The law directed the Secretary of Transportation to withhold a portion of federal highway funding from any state that allowed people under 21 to purchase or publicly possess alcohol. Every state eventually complied. The law also established the template Washington has used ever since: states technically set their own DUI policies, but federal highway dollars give Congress enormous leverage.
The 0.08% Standard Goes National
Through the 1990s, the legal BAC threshold in most states was still 0.10%. Research consistently showed that impairment begins well below that level. Congress responded with the Transportation Equity Act for the 21st Century, known as TEA-21, signed into law in 1998. Section 1404 of the act created incentive grants under 23 U.S.C. 163, offering federal money to any state that made it a per se offense to drive with a BAC of 0.08% or higher.1Federal Highway Administration. TEA-21 – A Summary – Improving Safety
TEA-21 also carried a stick. States that failed to prohibit open containers in vehicles and set minimum penalties for repeat drunk drivers faced a transfer of highway construction funds to safety programs, starting at 1.5% in 2001 and rising to 3% each year after.1Federal Highway Administration. TEA-21 – A Summary – Improving Safety By the mid-2000s every state and the District of Columbia had adopted 0.08% as the per se limit.
Congress imposed additional requirements for repeat offenders through 23 U.S.C. 164, which conditions highway funding on states maintaining minimum penalties for second and subsequent DUI convictions. Those minimums include at least a one-year license suspension or restriction to vehicles equipped with an ignition interlock device, a substance abuse assessment and treatment, and either community service or jail time that escalates with additional offenses.2Office of the Law Revision Counsel. 23 USC 164 – Minimum Penalties for Repeat Offenders for Driving While Intoxicated or Driving Under the Influence
Zero Tolerance for Underage Drivers
Alongside the push for lower adult BAC limits, the 1990s saw the adoption of zero tolerance laws for drivers under 21. The logic was simple: underage drinking is already illegal. These laws typically set the BAC threshold at 0.02% or lower, and most states enacted them by the late 1990s after the federal government tied highway safety funding to their adoption.
Ignition Interlock Devices
The first court-ordered installation of an ignition interlock device happened in Denver in 1985. These devices require the driver to blow into a breath-testing unit before the engine will start. If the device detects alcohol above a preset limit, the car stays off.
Adoption was slow at first, limited to pilot programs and repeat offenders. Federal policy accelerated it. Under 23 U.S.C. 405(d), the Department of Transportation offers impaired-driving countermeasure grants to states that enact ignition interlock laws.3eCFR. 23 CFR 1200.23 – Impaired Driving Countermeasures Grants In 2013, the National Highway Traffic Safety Administration released model guidelines urging states to require interlocks even for first-time offenders. Currently, 31 states and the District of Columbia require interlock installation for all DUI offenders, including those convicted for the first time.4National Conference of State Legislatures. State Ignition Interlock Laws
Drug-Impaired Driving Laws
For most of the 20th century, DUI enforcement focused almost exclusively on alcohol. Every state now prohibits driving while impaired by drugs, but the laws vary dramatically in how they define the offense. Some states follow the alcohol model: if you are visibly impaired, you are guilty regardless of what caused it. Others have adopted per se limits for specific drugs, particularly THC. Six states set per se THC thresholds, typically at 2 or 5 nanograms per milliliter of blood, while twelve states take a zero-tolerance approach that criminalizes any detectable amount of THC or its metabolites in a driver’s system.
These per se drug limits remain controversial. Unlike alcohol, where the relationship between BAC and impairment is well established, THC can linger in the blood long after its impairing effects have worn off, particularly in regular users. The science is genuinely unsettled, and state legislatures are still experimenting.
Utah’s 0.05% Law and What Comes Next
The most recent major development came from Utah, which in 2017 passed legislation lowering its per se BAC limit from 0.08% to 0.05%. The law took effect on December 30, 2018, making Utah the first state to adopt the lower threshold. NHTSA studied the law’s early impact and found promising results for road safety during its first year of implementation.5National Highway Traffic Safety Administration. Utah’s .05% Law Shows Promise to Save Lives, Improve Road Safety
No other state has followed Utah’s lead so far. The National Transportation Safety Board recommended a nationwide 0.05% standard in 2013, and the idea continues to circulate in state legislatures. Whether 0.05% becomes the next national standard the way 0.08% did remains an open question. The pattern from previous decades suggests that if early-adopting states show measurable safety gains and federal incentive money materializes, the rest will eventually follow.