This opinion clarifies the distinction between Professional Real Estate Investors, Inc. v. Columbia Pictures Industries, Inc. (1993) 508 U.S. 49 and USS-POSCO Industries v. Contra Costa Cnty. Bldg. & Constr. Trades Council (9th Cir. 1994) 31 F.3d 800 in the application of the sham exception to the Noerr-Pennington doctrine. Prof. Real Estate applies when the defendant has commenced only one or a very few “proceedings.” It requires proof of lack of probable cause before the plaintiff can get to the also-required element of improper motive. POSCO applies in the relatively rare situation of multiple (there, 29) repetitive suits. For purposes of counting and thus deciding which of these decisions applies, a “proceeding” is an entire lawsuit or administrative proceeding, not particular motions or appeals within the same lawsuit or administrative proceeding. Here, the district court properly dismissed the case finding that the four challenges defendants had brought under CEQA to challenge plaintiff’s hotel projects were not clearly baseless so as to fall within the sham exception to Noerr-Pennington.