I once was thinking about creating a profile or community called "Hive Police" to do this work, with a list of very direct rules to be applied and full interface to vote for blacklisting. And all blacklisting would need to have a Hive end-block number when the name would be removed.
Example:
- "current block number" + 201600(a week from now) = end-block number
- "current block number" + 864000(a month from now) = end-block number
Also the gravity of the infraction would determine if the profile from just blacklisted to receive a warning to would have automatic downvotes on everything it posts before the end-block
To determine if someone gets blacklisted there would be a 4-day vote among all profiles delegating HP to the Hive Police where it would be necessary to have 75% voting-HP + 20% total delegator profiles FOR the inclusion. The included profile could appeal at any time, and if he manages to turn enough votes to go below the "guilty-threshold", his name is removed from the list
It's not a perfect system, but it was an idea I had.