Can I prevent a user from approving his own ticket?

When a privileged user submits a request to one of my RT queues on which
we have the Approval process established, is there any way to prevent
that user from approving his own ticket?

I have a select group of users set up as approvers for my Approvals
queue, but I can’t find anything to stop one of those “approver” users
from submitting an “approval” ticket and approving it himself.

Thanks,
Sharyn Z