In a video interview with SCOTUSblog, Randy Barnett lists clauses in the Constitution that have effectively been insulated from litigation:
Ask any constitutional litigators whether they can go into court and litigate the Ninth Amendment, the Privileges or Immunities Clause, or the Origination Clause, which states that revenue bills must originate from the House. Can they litigate the Contract Clause, in any but a small number of areas? Until recently they couldn’t litigate the Second Amendment. Can they litigate the Commerce Clause and the Necessary and Proper Clause? Yeah, only if Congress does something way, way out, and only until the Rehnquist Court in 1995.
And I haven’t even got to most of them.
One clause after another has been interpreted by the Supreme Court out of existence. When I read what the Supreme Court had done to what I consider to be the “good” parts of the Constitution, I decided that if the Supreme Court isn’t going to take the Constitution seriously then why should I? … In contracts, writings are taken more seriously, as is the doctrine. That’s the reason I became a contracts professor.