The league drug tests players at the NFL Combine every year and despite the fact that players know it's coming there are some that will fail. This year that list includes Georgia DE Justin Houston and Iowa DE Christian Ballard. Jay Glazer of FOXSports.com reports both players failed the Combine drug test for marijuana.
The news is just getting out now but teams have had this information so it's not news to everyone. It remains to be seen how this affects their draft stock. Marijuana doesn't mean a player can't be great and steer clear of any problems but it does raise a flag for those teams wondering how a player can know a drug test is coming and still fail it.
Houston is seen as a late first round pick so if he slips into the second round it's possible that's because the failed drug test scared a couple teams off. Or it's also possible he's still a first round pick and this doesn't affect how teams view him. Ballard is seen as a second round prospect so he's in a similar boat as Houston.
Neither player has a police record or long history of trouble so it's possible this is just a blip on the radar and it won't affect their draft stock.