How is evolutionist thinking used in interpreting the constitution?

There is no connection whatsoever between Biological Evolution and the interpretation of legal documents like the US Constitution.

As stated above the US Constitution itself specifies who will be allowed to interpret it: the Supreme Court. No other entity has the legal right to interpret the US Constitution. Not scientists, not congress, not the president, not average citizens, not special interest groups, etc.; only the Supreme Court.

The Supreme Court is only allowed to interpret the US Constitution using information from case law, legal precedences, the writings of the Founding Fathers on their intentions in writing the US Constitution, and other relevant legal documents in their decisions. The Supreme Court is not allowed to use personal opinions, scientific information, public poll results, evidence from the cases they are evaluating (the Supreme Court is an Appeals Court not a Trial Court and thus is not permitted to examine evidence in the case, only if procedural errors were committed or violations of the US Constitution occurred in the case), etc. in their decisions.