House Panel Advances Cannabis Impairment Standards Bill

The House Transportation and Infrastructure Committee cleared a sweeping bipartisan surface transportation bill on May 22, 2026 that includes provisions directing federal agencies to study cannabis-impaired driving and develop what the legislation calls “evidence-based impairment standards.” The bill — the BUILD America 250 Act — puts a decade-old scientific problem back on the federal agenda as legalization spreads across the states.

The committee approved the bill with wide bipartisan support, following a 14-hour markup session. It now advances toward a full House floor vote. Current federal transportation authorization expires September 30, 2026, and committee leaders on both sides said they expect floor passage before then.

What the Bill Directs

The cannabis-related provisions sit inside a 1,000-plus-page package covering roads, bridges, rail, and highway safety. The drug-impairment section would require the secretary of transportation to collaborate with other federal agencies to study “the effect that intoxicating cannabinoids and polysubstance impairment has on driving” — language that was updated during markup to replace an earlier version using “marijuana” specifically. The broader phrasing captures synthetic cannabinoids and mixed-substance impairment alongside plant-derived THC.

After completing the study, the agencies would be required to propose evidence-based impairment standards for intoxicating cannabinoids and polysubstance use, with the transportation secretary submitting a progress report to Congress.

A separate provision directs the department to establish a national drug-involved crash data collection system — gathering standardized toxicology data from states in fatal and serious-injury crashes, linking that data to medical and emergency services records, and developing model protocols for specimen collection, testing, and reporting. DOT could award grants to states to stand up pilot programs and support toxicology labs, funded at $110 million over fiscal years 2027 through 2031. The National Highway Traffic Safety Administration would also submit a separate report to Congress on collaborative research into impaired driving prevention technology.

Why Federal Impairment Standards Don’t Exist Yet

The legislative mandate is significant precisely because federal impairment standards for cannabis have never existed — and not for lack of effort. The science is genuinely hard. Unlike blood-alcohol concentration thresholds for alcohol, THC levels in blood don’t reliably predict impairment: peak intoxication doesn’t coincide with peak blood THC, and regular users can test positive for cannabinoids days after last use with no measurable effect on driving. NHTSA has previously told Congress in reports that no evidence-based methods exist to detect cannabis-impaired driving.

That gap matters at scale. More than half of drivers involved in serious injury and fatal crashes at studied trauma centers tested positive for at least one drug, according to NHTSA’s data from late 2020 — and cannabis prevalence in those datasets has grown alongside state-level legalization.

In the absence of a federal standard, states have gone different directions. Some have set specific THC blood-level limits, even though toxicologists widely note those thresholds don’t reliably indicate current impairment for all users. Others rely on behavioral testing and officer observation. The result is fragmented enforcement across state lines — and an ongoing challenge for courts that handle cannabis-related DUI cases.

This isn’t the first federal directive on the problem. Congress included a similar study requirement in the surface transportation act it passed in 2015. Much has changed since then: state-licensed medical marijuana was moved to a lower federal schedule under a DEA final order issued in April 2026 — though recreational and non-licensed cannabis remains at the highest federal restriction level — and more than two dozen states have now licensed adult-use retail. As MyCannabis reported earlier this month when the bill was introduced, the 2026 version brings updated language that accounts for the full class of intoxicating cannabinoids, not just conventional marijuana products.

What Happens After Committee Approval

The Transportation and Infrastructure Committee’s approval advances the bill to the full House. Committee Chair Rep. Sam Graves (R-MO) said after the markup that he plans to move the bill to the floor “in the near future” and work with the Senate before the September 30, 2026 deadline. Ranking Member Rep. Rick Larsen (D-WA) said he anticipates “swift passage by the full House.”

The bill’s cannabis provisions arrive against a backdrop of tightening federal enforcement around cannabis and work. Earlier this month, DOT issued guidance confirming that safety-sensitive workers — including truck drivers and airline pilots — cannot use medical cannabis even after rescheduling, because state-dispensed medical marijuana has not received FDA approval. Those workplace testing rules remain in place regardless of what the impairment study eventually produces.

What the study process could set in motion is broader than its transportation-safety framing suggests. A federal impairment standard — if one emerges — would likely shape how state DUI laws are written and enforced, how courts handle cannabis-related traffic cases, and what employers can legally require in drug-testing programs. The central question — whether impairment is measured behaviorally or through a chemical threshold, and whether a per se THC level is even scientifically defensible — has no settled answer.

Congress is asking federal agencies to find one.