[meta] Policy for dealing with users suspected/​guilty of mass-downvote harassment?

Below is a message I just got from jackk. Some specifics have been redacted 1) so that we can discuss general policy rather than the details of this specific case 2) because presumption of innocence, just in case there happens to be an innocuous explanation to this.

Hi Kaj_Sotala,

I’m Jack, one of the Trike devs. I’m messaging you because you’re the moderator who commented most recently. A while back the user [REDACTED 1] asked if Trike could look into retributive downvoting against his account. I’ve done that, and it looks like [REDACTED 2] has downvoted at least [over half of REDACTED 1′s comments, amounting to hundreds of downvotes] ([REDACTED 1]‘s next-largest downvoter is [REDACTED 3] at −15).

What action to take is a community problem, not a technical one, so we’d rather leave that up to the moderators. Some options:

1. Ask [REDACTED 2] for the story behind these votes
2. Use the “admin” account (which exists for sending scripted messages, &c.) to apply an upvote to each downvoted post
3. Apply a karma award to [REDACTED 1]‘s account. This would fix the karma damage but not the sorting of individual comments
4. Apply a negative karma award to [REDACTED 2]’s account. This makes him pay for false downvotes twice over. This isn’t possible in the current code, but it’s an easy fix
5. Ban [REDACTED 2]

For future reference, it’s very easy for Trike to look at who downvoted someone’s account, so if you get questions about downvoting in the future I can run the same report.

If you need to verify my identity before you take action, let me know and we’ll work something out.

-- Jack

So… thoughts? I have mod powers, but when I was granted them I was basically just told to use them to fight spam; there was never any discussion of any other policy, and I don’t feel like I have the authority to decide on the suitable course of action without consulting the rest of the community.