As Apollyon and others note, formerly banned users who return are generally rebanned.
However, we do not go looking for them so usually there is a behavior pattern or complaints which result in us finding out who they are/were. This was the case with CorpusERDoc. Depending on the reason for the original ban, there are lengthy discussions which happen at the Mod level and clearly defined ladder of administrative action. Thus, some returnees are allowed to stay but are told that they must toe the line and any additional TOS violations or actions for which they were previously banned results in a ban of their new account.
Rockford/CorpusER was OSU and was told multiple times of the expected behavior which he continued to violate; some threads have been edited or removed and of course, the general usership is not privy to PMs from him which may have violated the TOS. We do not discuss the exact reasons for banning with anyone except the user in question in keeping with our privacy policy.
Regular users should not be afraid that they are going to be banned indiscriminately. There is actually a fairly routine process through which an individual moves before getting banned - the exceptions being SPAM and return bannees that immediately start trolling. It starts with a warning and escalates through a point system to post-hold of varying lengths and then banning. Most users will never move beyond the warning step. Previous infractions are not counted if they have occurred a certain length of time in the past, unless they are especially aggregious and the user continues to exhibit the same behavior.
We try and be consistent but there is no way, especially with the large number of staff members we have, that it is going to be all the time. But in the case of banning individuals, members can rest assured that there is a staff discussion which occurs and decisions are not made unilaterally and in haste. It may not seem that way but honestly, with the exception of Spammers, regular users are not banned very often. It just seems like it because some of those who are, are very prolific (ie, OSU, JPH) and are known site wide.
