Personally I think any urine test should be illegal under the fifth amendment(we have a similar statute in Canada) against self incrimination and all drug use should be legal for adults.
I don't see any difference between someone saying that they should be allowed to own a gun as a responsible adult and someone saying that they should be allowed to
decide what drugs they put in their system as a responsible adult. Some people here feel they don't want to use drugs so why should anyone else be allowed?
That is no different than some san fransisco liberal saying you should not be allowed to own guns because he does not feel the need for them.

Prohibition did not work with alcohol and it is definitly not working with drugs.
Neither drugs or guns are harmfull when used responsibly. When people use either of them irresponsibly they should be punished according to the harm they cause and should not be able to blame either drugs or "gun violence" for their own actions.

People should be held responsible for their actions and have absolute freedom so long as it does not interfere with someone else's.