How to use "plainly" in a sentence

The clause I now read is as plainly written in the Constitution as any other of its provisions:

Is it true, then, that any right, plainly written in the Constitution, has been denied? I think not

Think if you can, of a single instance in which a plainly written provision of the Constitution has ever been denied

All the vital rights of minorities and of individuals are so plainly assured to them by affirmations and negations, guaranties and prohibitions, in the Constitution, that controversies never arise concerning them