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Colorado State Troopers perform a road side sobriety test. Photo: Andy Cross / Getty

With states continuing to legalize or decriminalize marijuana, scientists and entrepreneurs are rushing to invent a marijuana breathalyzer that would detect whether someone was impaired while driving, according to STAT, instead of relying on more subjective sobriety tests.

The key problem: While urine and blood tests can show whether someone has used marijuana, they can't test impairment. While some states have set a legal limit of THC for drivers, some experts say that frequent smokers could pass the THC level without actually being impaired, according to STAT.

One new idea: Massachusetts General Hospital researchers are working on a cap, which would use a technique called functional near infrared spectroscopy (fNIRS) to detect changes in blood flow in the brain. The researchers hope to establish patterns in the brain when subjects are high.

Driving high: Many people feel more aware and more capable of driving when stoned than they do when drunk. Dr. Mike Lynn, the CEO and co-founder of Hound Labs, which is working on a marijuana breathalyzer, told STAT that when his lab had people who were high on marijuana drive through an obstacle course, “all of them hit that cyclist when they were stoned, and most of the time, they didn’t even know they’d hit him.”

Go deeper with STAT's full piece.

Go deeper

In photos: D.C. and U.S. states on alert for pre-inauguration violence

National Guard troops stand behind security fencing with the dome of the U.S. Capitol Building behind them, on Jan. 16. Photo: Kent Nishimura / Los Angeles Times via Getty Images

Security has been stepped up in Washington, D.C., and state capitols across the U.S. as authorities brace for potential violence this weekend.

Driving the news: Following the Jan. 6 insurrection at the U.S. Capitol by some supporters of President Trump, the FBI has said there could be armed protests in D.C. and in all 50 state capitols in the run-up to President-elect Joe Biden's inauguration Wednesday.

14 hours ago - Politics & Policy

The new Washington

Illustration: Sarah Grillo/Axios

The Axios subject-matter experts brief you on the incoming administration's plans and team.

Rep. Lou Correa tests positive for COVID-19

Lou Correa. Photo: Tom Williams/CQ-Roll Call, Inc via Getty Images

Rep. Lou Correa (D-Calif.) announced on Saturday that he has tested positive for the coronavirus.

Why it matters: Correa is the latest Democratic lawmaker to share his positive test results after last week's deadly Capitol riot. Correa did not shelter in the designated safe zone with his congressional colleagues during the siege, per a spokesperson, instead staying outside to help Capitol Police.