Some examples of relevant subject tags used in journal article databases:
Specific focus:
UNITED States Constitution 1st Amendment
FIRST Amendment protections (United States Constitution)
More general:
CONSTITUTIONAL amendments United States
EQUAL rights amendments
etc.
Note: subject tags used might vary somewhat from one database to another. Tags such as
UNITED States Constitution 1st Amendment
are pretty reliable, however.
Some examples of relevant subject tags used in library catalogs (such as CLIO, etc.):
Specific focus:
United States Constitution 1st Amendment
United States Constitution 2nd Amendment
United States Constitution 8th Amendment
More general:
Constitutional amendments United States
EQUAL rights amendments