Under federal patent law, a patent owner may receive only one period of exclusivity for its invention and may not obtain a second patent on the same invention or a "colorable variation" thereof. McCreary v. Pa. Canal Co., 141 U.S. 459, 467 (1891). The question presented is:

May the patent owner avoid the rule against double patenting by buying all of the substantial rights to a second, later-expiring patent for essentially the same invention, so long as the seller retains nominal ownership and a theoretical secondary right to sue for infringement?

May the patent owner avoid the rule against double patenting by buying all of the substantial rights to a second, later-expiring patent for essentially the same invention, so long as the seller retains nominal ownership and a theoretical secondary right to sue for infringement?