There's lots of that to go around.
Michael Schiavo's star witness was a neurologist named Ronald Cranford. He testified that Terri was indeed in a PVS and Greer accepted his testimony as convincing. Problem is, he's a well-known euthanasia who is a professional witness in cases like this, always testifying that patients are in a PVS.
One of his patients, Robert Wendland, could operate his own wheelchair and pick up colored blocks correctly, but that didn't stop Cranford from testifying to his PVS state. Fortunately the CA Supreme Court didn't buy it.
He's had patients recover from PVS after he's diagnosed them with it. And he openly admits that he doesn't feel anyone should have a feeding tube, says that a spoon is often artificial life support, and doesn't believe advanced alzheimers patients or PVS patients have constitutional rights.
Should he have been trusted as a credible witness in this case?