The term _jury_ is a technical one, derived from the common law; and when the American constitutions provide for the trial by jury, they provide for the _common law_ trial by jury; and not merely for any trial by jury that the government itself may chance to invent, and call by that name. It is the _thing_, and not merely the _name_, that is guarantied. Any legislation, therefore, that infringes any _essential principle_ of the _common law_, in the selection of jurors, is unconstitutional; and the juries selected in accordance with such legislation are, of course, illegal, and their judgments void. It will also be shown, in a subsequent chapter,[79] that since Magna Carta, the legislative power in England (whether king or parliament) has never had any constitutional authority to infringe, by legislation, any essential principle of the common law in the selection of jurors. All such legislation is as much unconstitutional and void, as though it abolished the trial by jury altogether. In reality it does abolish it. What, then, are the _essential principles_ of the common law, controlling the selection of jurors? They are two. 1. That _all_ the freemen, or adult male members of the state, shall be eligible as jurors.[80] Any legislation which requires the selection of jurors to be made from a less number of freemen than the whole, makes the jury selected an illegal one. If a part only of the freemen, or members of the state, are eligible as jurors, the jury no longer represent "the country," but only a part of "the country." If the selection of jurors can be restricted to any less number of freemen than the whole, it can be restricted to a very small proportion of the whole; and thus the government be taken out of the hands of "the country," or the whole people, and be thrown into the hands of a few. That, at common law, the whole body of freemen were eligible as jurors is sufficiently proved, not only by the reason of the thing, but by the following evidence: 1. Everybody must be presumed eligible, until the contrary be shown. We have no evidence, that I am aware of, of a prior date to Magna Carta, to _disprove_ that all freemen were eligible as jurors, unless it be the law of Ethelred, which requires that they be elderly[81] men. Since no specific age is given, it is probable, I think, that this statute meant nothing more than that they be more than twenty-one years old. If it meant anything more, it was probably contrary to the common law, and therefore void. 2. Since Magna Carta, we have evidence showing quite conclusively that all freemen, above the age of twenty-one years, were eligible as jurors. The _Mirror of Justices_, (written within a century after Magna Carta,) in the section "_Of Judges_"--that is, _jurors_--says: