The National Football League has an annual window in which it is allowed to test athletes for marijuana use and that window just so happened to open today...on 4/20. 

Funny enough, the testing window does not cover "recreational drugs" during the season (because the players need it to recover after games of course). But the rules can be altered for a number of reasons depending on when a player was signed and if they are a rookie or not, so not everybody is off the hook. 

There is a big contingency of people who think the rules need some changing considering they were made many years ago, but the league has yet to budge. 

Check out the NFL's full set of drug policies here and of course, have a Happy 4/20!