I have 57 cases solved, elo 2171 with 88% of accuracy and I'm still unranked. I'm curious how many cases until I am "ranked" judge. Anyone know anything more about it?
Since there is no clear guideline from Riot you can only estimate. One thing is certain: To become ranked you need to be in the top 1000 Tribunal Ratings. Check this thread out at Western European Server where people compare their Ratings: http://euw.leagueoflegends.com/board/showthread.php?t=896598
You'll see there that by estimation you need about 8k Rating to be close to becoming ranked. But that of course was 5 days ago and it will probably keep changing since it's a relatively small and apparently pretty competitive ladder.
It also depends on the region so the thread I gave you only refers to Europe West. But if you go through the posts a bit you will get the general idea.