What is the test for a summary dismissal of a pro se petition?

Rule 4 of the Rules Governing Section 2254 Cases provides for preliminary consideration of habeas petitions by district court judges. In pertinent part, the rule states "[i]f it plainly appears from the face of the petition and any exhibits annexed to it that the petitioner is not entitled to relief in the district court, the judge shall make an order for its summary dismissal ...." Given the increasing number of pro se petitions filed each year--many of which are inartfully drafted--we can appreciate a busy district judge's possible predilection toward summary dismissal. Nevertheless, Rule 4 does not confer unbridled discretion to dispose of all such habeas applications sua sponte. Summary dismissal is appropriate only in those cases where the pleadings indicate that petitioner can prove no set of facts to support a claim entitling him to relief. See Conley v. Gibson, 355 U.S. 41, 45-46, 78 S.Ct. 99, 101-102, 2 L.Ed.2d 80 (1957).