Hello all,
I hope this is the correct place to ask this. One of the regular players at the lgs where I usually judge asked if there were any rules around being sponsored by a Buisness and wearing their appearal to a GP. (it is a hemp buisness). I didn't know so I thought I would ask.

Sounds more like a decision for the TO. As long as the apparel isn't offensive, they should be fine.

Sponsorship is absolutely fine; many players wear team or other branded apparel at GPs.

The specific company involved may be of concern so I would concur with Paul that the player in question should contact the organizer of any event at which he intends to play.

…and I'll come along and confirm that the unofficial but hasty answers are fine - have him contact the TO first, to make sure there's no concerns. If it's just logos on clothing, playmat, sleeves etc., it should be fine. If he intends to hand out fliers or business cards, the TO may consider him a vendor; all those other vendors pay a fee to be there.

d:^D