When is a Motion for Judgment on the Pleadings Converted to a Motion for Summary Judgment?

Hernandez v. Coffey, 06-4246 (2d Cir. Sep 21, 2009) (here) discusses whether a Rule 12(c) motion for judgment on the pleadings may be converted to a motion for summary judgment when pro se litigants are involved.  The panel held that a trial court could not assume a pro se litigant understood this stuff:

In sum, before the court converted the defendants’ motion for judgment on the pleadings into a motion for summary judgment and granted that motion, extinguishing the pro se plaintiff’s claim, the plaintiff was entitled to (i) an opportunity to take relevant discovery and to submit any evidence relevant to the issues raised by the motion, and (ii) absent a clear indication that he already possessed such understanding, an explanation of the consequence of a grant of summary judgment, as well as of what he could do to defeat the motion.