User blog comment:Brandon Rhea/Bringing down the banhammer: Best practices for blocking/@comment-1318845-20120316203413/@comment-20644-20120316205401

Personally, I would advise against unblocking a user another admin has already blocked unless you've already talked with that admin. Unless an administrator is acting really recklessly to the point where it's harming the wiki, administrators should be afforded some autonomy.

The best thing to do, as an administrator, if you disagree with another administrator's block is to talk to that administrator about it. If you can reach an agreement, then that's the preferred outcome. If you can't, you can always talk to any other administrators to try and come to some sort of group consensus, or (if necessary) leave it up to the community.