Obviously, as Randall points out in the title text, his bracket is busted since he had Massachusetts v. Connecticut in the final, but I got to wondering, can we complete the bracket using actual cases to determine the victor?
Sweet SixteenMadison v. McCulloch - no such case. The closest I can find is a set of Iowa Supreme Court cases from the 1960's dealing with redistricting in the wake of the one man-one vote ruling.
Kruidenier v. McCulloch have et al.'s for both parties, but no Madison is amongst Kruidenier et al. nor is there a clear victor.
Gibbons v. Near - no such case, but I did find a California Surpreme Court case from 1928,
People v. Gibbons. Presumably there was at least one person named Near living in California, so I'll use this case, which Gibbons won.
NLRB v. Brown, 380 U.S. 278 (1965) - Brown won
Gideon v. Griswold - no such case, and I didn't find anything even close to it.
I'm going to stop here for now. There's only one clear case out of the four I've looked for so far. It would be interesting to construct actual bracket that could be completely decided by Supreme Court case results, but this bracket ain't it.