In Louisville & Nashville Railroad Co. v. Mottley (1908), we get the well pleaded complaint rule: cases arise under federal law, as that phrase is used in 1331, if the federal issue appears on the face of the well-pleaded complaint, that is, if a proper complaint, limited to the allegations necessary to state a proper claim for relief, relies on federal law.

How does the well-pleaded complaint rule avoid "gamesmanship" among litigants? Explain.