The Constitution doesn't say that the Supreme Court is the final say?

Constitution, Article 3

> The judicial Power of the United States, shall be vested in one supreme Court, and in such inferior Courts as the Congress may from time to time ordain and establish. The Judges, both of the supreme and inferior Courts, shall hold their Offices during good Behaviour, and shall, at stated Times, receive for their Services, a Compensation, which shall not be diminished during their Continuance in Office.

If your question was intended to claim that the Article you quoted gives The Supreme Court ‘the final say on legal interpretation,’ I’m interested to know which words in that Article you believe gives that say.