I don’t believe that many Jiu-Jitsu players compete in Judo tournaments, because most of them require you to be a member of USJA or USJF. However, Nebraska’s State Games has no such requirement, so it’s open to all. Last summer when I competed, I was one of a handful of Jiu-Jitsuka. During the rules meeting, a couple of them were admonished for having illegal gis, and they were told that if they did not find proper gis they would not be allowed to compete.
While I am not at all happy with the way they were treated, the fact remains that if they had read the rules, they would have known that their gis would not be allowed. You can compete in pretty much any Jiu-Jitsu tournament wearing a Judo gi, but many Jiu-Jitsu gis are not legal in Judo tournaments. They have very specific rules concerning gis; down to the length of it, the number of patches and placement, the color (only blue or white), etc.
If you’re planning to compete in any tournament, you should always read through all of the rules. Luckily those two Jiu-Jitsu guys were able to use loaner gis, so they didn’t lose their chance to compete (and their entry fee) and over such a small thing as not being dressed right.
By the way, if you want to compete in the Ne State Games Karate competition, you can wear any gi you like. You can dress as a Power Ranger if you want, we don’t care (although we may laugh at you). You don’t even have to do Karate, you can do Kung Fu, or Taekwondo, or Crazy White Lady (that’s my personal competition style), as long as you follow the rules. Like my dad used to say “Ignorance of the law is no excuse.”