Harm Reduction Needle Exchange Cards

Is it worth going to a needle exchange to get those cards that people carry allowing them to possession syringes? I had a friend who went to Cornell and went to a place in Ithaca where he got syringes, cottons, water ampoules, metal mixing caps, alcohol swabs, and a few rubber tourniquets. I don't need that stuff I am more interested in the card. As far as I remember it just had his name and the name of the program.

How does these places work? Do cops actually respect these cards?

They are supposed to in localities with laws protecting card holders.

Is it common for this type of stuff to be illegal? I would look into it before traveling, but my name isn't on any of my IV medication as it's not from a pharmacy, the clinic hands it out, along with all of the other supplies I need. They just jot part of my name on a paper bag in sharpy to make sure I'm getting my supplies.

I just didn't think that this would be an issue for most first world countries.