Motive becomes keenly relevant in cases that involve content discrimination because the line between viewpoints and subjects is such an elusive one. Because subject matter discrimination is clearly constitutional in nonpublic fora,
see Perry, 460 U.S. at 49, 103 S.Ct. at 957, classifying a particular viewpoint as a subject rather than as a viewpoint
on a subject will justify discrimination against the viewpoint. This inherent manipulability of the line between subject and viewpoint has forced courts to scrutinize carefully any content-based discrimination.
See Air Line Pilots Ass'n v. Department of Aviation, 45 F.3d 1144, 1159–60 (7th Cir.1995) (warning courts against retreating to an exaggerated level of generality when examining content-based regulations). Courts thus have struggled, for example, with the issue of whether religious discussion should be categorized as a subject (and therefore excludable from a nonpublic forum) or as a viewpoint (and therefore constitutionally protected).
See Rosenberger, 515 U.S. at –––– – ––––, 115 S.Ct. at 2517–18;
Grossbaum I, 63 F.3d at 589–92. The Supreme Court faced a similar issue in
Cornelius where it was understandably dubious of the argument that excluding all advocacy groups, regardless of political orientation, from a government charity drive was just subject matter discrimination rather than viewpoint discrimination.
473 U.S. at 811–12, 105 S.Ct. at 3454. Because the government was distinguishing among groups based on the content of their messages (either advocacy or nonadvocacy), the Court remanded the case to see whether the government was really targeting certain viewpoints.