The Coast Guard won't have access to your rec (your letter of recommendation signed by a doctor). Don't offer information. If you had criminal charges against you, you would have something serious to worry about. Your mmj rec (medical marijuana letter of recommendation) isn't an offense. I have known a few people who went into the armed forces after testing positive for weed. Their recruiter just gave them more time and had them retest.
It is quite unfortunate that a young person willing to spend two years or four years away from their family and the things they personally enjoy for a country that disallows marijuana but allows (and seems to encourage) cigarettes.
It's obscene.
Just sign up for the Coast Guard, make sure you test negative, and don't offer information. If asked point blank if you have ever used drugs or alcohol, it's not like you are the ONLY one who answers yes! In fact I wish everyone everywhere answered yes to that question... then maybe governments would be forced to realize they failed.
I would love it if you came back to this board and posted about what happened when you went to see a/your recruiter from the Coast Guard.
I tried to buy a life insurance policy a few years ago. A nurse came to my home, took my vitals and various samples. About a month later I received a letter from the insurance company that I tested positive for marijuana. I countered with a copy of my rec and a strongly worded letter, to no avail. In fact I can't get good life insurance at any cost. Apparently I am more of a danger to myself because I use weed than I would be if I drank alcohol.
The sixties were going to be the revolution, but we failed. It is going to take everyone making an issue out of mmj at every opportunity, if we are ever going to be allowed to stop all this hiding the weed bullshit we live through all the time.