Illinois decriminalized Marijuana!

[Igel]

25. It also impairs memory formation

and reflexes for more than 24 hours after use.

That first bit, memory formation, means it likely hurts students. We see high-achievers who still do well, even if it probably reduces their achievement a bit, but we miss the bottom quartile who aren't doing well to begin with. It doesn't impair intelligence. Just what's learned. Since tests measure not intelligence but what's learned, well, you see the problem.

Strictly speaking, that's a deduction. Pot research hasn't been done on minors because that doesn't get past the protocols board.

The second is also intriguing, because if the test results for THC come back under the minimum legally prescribed, those results aren't recorded. But since it slows reaction time, we should deduce until proven otherwise that this residual effect increases accident rates. Studies looking at accidents and pot use focus either on overall stats, not showing blood levels below the legal minimum or drivers currently clearly under the influence. In other words, there's a gap that people argue is neutral.