Competitions and gradings will be held by the US governing body for Judo.Its USA Judo Also i think there is a USJF. I am a brit so governed by the BJA, this is the olympic organisation. Everyone falls into line with the IJF (International Judo Federation). The olympic body for the US is USA Judo

http://www.usjudo.org/

Ive just done a search on detroit michigan going through the USA Judo site and its brought up the Michigan Judo site (seems each state has a governing body as such that falls in line with the USAJ body...dang you guys do things complicated)

Anyway..have a look here http://www.michiganjudo.org/ListDojo...tate=MI&area=1 its a list of dojo's in the michigan area. May be out of date and not helpful , who knows. It might however be worth giving them a call and asking when the next grading or comp is so you can pop along and watch. I did click on the Detroit section so hopefully these dojo's are near to you.

Sorry can't be more helpful