on the i4i/Microsoft case

The question presented in the i4i case is as follows:

Whether, when the defendant in an infringement suit
asserts as a defense that the relevant patent is invalid,
the defendant must prove invalidity by clear and con-
vincing evidence.

The US government brief notes:

The Federal Circuit has long held that, in order to
rebut the presumption of validity, the party challenging
the patent must establish invalidity by clear and con-
vincing evidence. See, e.g., American Hoist & Derrick
Co. v. Sowa & Sons, Inc., 725 F.2d 1350, 1359-1360,
cert. denied, 469 U.S. 821 (1984). The court has applied
that heightened standard even when the defendant in-
troduces evidence of invalidity that was not before the
PTO during the examination process. See ibid. The
court has recognized, however, that “new” evidence may
“carry more weight and go further toward sustaining
the attacker’s unchanging burden.” Id. at 1360.

See also
Obama Administration to the Supremes: Judges
Should Defer to U.S. Patent and Trademark Office Expertise