We have covered Pfizer’s development of biosimilars of Genentech’s Avastin® (bevacizumab) and Herceptin® (trastuzumab) and its related IPR filings IPR2016-01771 and IPR2016-01837. Following written decisions invalidating those two patents, Genentech appealed and challenged the constitutionality of subjecting patents that issued before the America Invents Act (AIA) was enacted in 2011 to inter partes review. The Federal Circuit had certified Genentech’s constitutional challenges to the U.S. Attorney General and directed the Attorney General to inform the Court whether the United States intended to intervene in the appeals. In unopposed motions to intervene, (here and here), the Attorney General moved to “exercise its statutory right to intervene in this appeal under 28 U.S.C. § 2403(a) to defend the constitutionality of the Act of Congress that appellant challenges.” The Federal Circuit granted the motions (here and here) and ordered the appellee and the United States to provide responsive briefs by November 5, 2018.