If a statute should give the right to take exceptions to the Government, I believe it would be impossible to maintain that the prisoner would be protected by the Constitution from being tried again. He no more would be put in jeopardy a second time when retried because of a mistake of law in his favor than he would be when retried for a mistake that did him harm. It cannot matter that the prisoner procures the second trial. In a capital case, like Hopt v. People, a man cannot waive, and certainly will not be taken to waive without meaning it, fundamental constitutional rights. Thompson v. Utah, 170 U. S. 343, 170 U. S. 353, 170 U. S. 354. Usually no such waiver is expressed or thought of. Moreover, it cannot be imagined that the law would deny to a prisoner the correction of a fatal error unless he should waive other rights so important as to be saved by an express clause in the Constitution of the United States.