Drugs are not a concern at all. Because of the contained environment, the only time that cadets really even have access to drugs is when they are on leave. After every block leave, there is usually a drug test, so if a cadet does drugs while they are on leave, there is a very good chance that they will get caught. And if a cadet gets caught, he will be dismissed. It's a very simple policy at West Point—absolutely no drugs allowed. The Academy will redefine strictness, and if you have a problem with authority, this is not the place for you.
The consensus among cadets is that drugs are not a concern on campus; the only drugs that you see on campus are tobacco products and alcohol. Punishments against excessive or irresponsible use are enforced, and they are very black and white. There is no way to "get out of it" at West Point—you can't talk your way out of a positive urine test. Don't expect a second chance at the Academy because you won't get one.