Which supreme court case allowed for first amendment free speech rights for corporations and labor unions, thus allowing them to give unlimited amounts of money to superpacs?

Citizens United vs the Federal Electoral Comission

Explanation:

This is probably one of the most polemic Supreme Court Decisions of all time. In this landmark case, the SCOTUS ruled that corporations, labor unions, and other forms of associations could not have their right to free spech, protected under the First Amendment, infringed, and that the protection also applied to political donations, because donating money to a politician si a form of free speech.

This decision effectively allows corporations and labor unions to give unlimited amounts of money to political campaigns.

in griswold v. connecticut (1965), the supreme court ruled that a state's ban on the use of contraceptives violated the right to marital privacy.