I am pretty sure it is legal - I've known lots of people to use it. It is a few drops in their mouth or you can put it in water I think? I know someone who eneded up giving their horse far to bigger dose and it ended up practically falling asleep so be careful!
I have used 6 drops on a piece of apple about half an hour before we get on my yougster. It seems to chill him out a bit.I can't say whether its comp legal though. Might be wise to get in touch with the BSJA or whoever to find out. I know valerian is a banned substance - that has a calming influence but whether that is in the rescue remedy I don't know.
I'm not being funny but unless your at top level SJ or eventing who the heck cares if its legal or not. I am not suggesting people cheat at competitions i.e by changing a sucessful horses name, or saying their horse has won less than it actually has, but I think i can say with 110% certainty that the local riding club will not be introducing dope testing on either horse or rider combinations at local level!
I used to take beta blockers for my terrible migraines when I competed under BSJA rules but I had not choice - I had a terrible life before I started taking them with really bad sickly headaches and hot flushes. Unfortuantely beta blockers also stop anxiety (so you could say I had an unfair advantage). To be honest I was only competeting at BN and Disc so it was hardly the crime of the century, I was more concerned in case I came off, got knocked out and the paramedic read my medic alert necklace I had around my neck and discovered I was on beta blockers and grassed me up to the judge! I cant see how giving rescue remedy can be illegal. What about all these 'magic' calmers with magnesium???
I honestly think if you ring up the BSJA or BD or BE and ask them about rescue remedy half of them will not have heard of it and the other half with fall off their chairs with laughter.