Just read a thread about this,who can give another a black belt,do you need three stripes ?
Depends on the school/organization. I know some that the candidate has to appear before a board of at least 3 BB's. I know of 1 school that to promote someone to BB only a 3rd degree BB can do it.
3 stripes and the approval of a master-cbjj rules
In most of the arts I have trained in, you can only promote up to one rank lower than your current belt level, and be a certified instructor.