The trial of a case in court results in a verdict and judgment or decree in favor of one party and against the adverse party. It very frequently follows that the one against whom the judgment or decree is rendered, carries the case to the appellate court. In appealing his case, the party alleges that the trial court committed certain error or errors, and that judgment or decree was rendered against him wrongfully. Perhaps it is alleged the trial court erred in its decision as to what the law was which governed the case. Again it may be alleged that the court erred in excluding or admitting certain testimony; or it may be alleged that a certain statute (law) which seemed to govern the case decisively, is unconstitutional, etc.
Upon the submission of the case in the appellate court, that court decides whether the acts of the trial court were erroneous; if not, the case is affirmed; otherwise it is reversed. So far as any conflict of any statute or law with the Constitution is concerned, the Constitution is supreme. Any act passed by the legislature which is contrary to the Constitution is said to be unconstitutional, and therefore null and void, although such an act may be passed and subsequently placed upon the statute-book, and thenceforth become apparently the law of a State, or of the United States, as the case may be.
This law, as it appears upon the book, is implicitly believed to be the law by many, or nearly all, for a considerable period of time; possibly it is universally conceded to be the law, and men conduct their affairs and themselves in accord with this law. In time, however, one party brings a suit in court against a second party, in which the law in question is involved, and if it be a valid law the second party can do nothing; judgment will be rendered against him and he must suffer the consequences. The case comes to trial; the second party, known as the defendant, denies the validity of this law, and asserts that it is contrary to the Constitution, therefore void and of no force or effect, and that he is not governed by it in any manner or degree. The trial court decides against him, and the case is appealed on the ground that this action of the court is error and therefore the case should be reversed.