For decades the same test has been used to convict drunk drivers.
Police ask a driver to stand on one leg, walk a straight line and recite the alphabet. If the driver fails, the officer will testify in court to help make a case for driving under the influence.
But defense lawyers argue, science has yet to prove that flunking the standard field sobriety test actually means that a person is high, the way it's been proven to measure drunkenness.
So, as attorney Rebecca Jacobstein argued to the Massachusetts high court, the tests shouldn't be allowed in evidence.
"If there's reliable science, reliable science gets to come in," Jacobstein argued. "It's just that unreliable science does not."
Prosecutors like attorney Michelle King don't agree. They argue that rapidly advancing science does prove field tests' reliability.