It is undoubtedly a very important problem in political ethics, whether great offences against the commonwealth may not justly incur the penalty of death by a retrospective act of the legislature, which a tribunal restrained by known laws is not competent to inflict. Bills of attainder had been by no means uncommon in England, especially under Henry VIII.; but generally when the crime charged might have been equally punished by law. They are less dangerous than to stretch the boundaries of a statute by arbitrary construction. Nor do they seem to differ at all in principle from those bills of pains and penalties, which, in times of comparative moderation and tranquillity, have sometimes been thought necessary to visit some unforeseen and anomalous transgression beyond the reach of our penal code. There are many, indeed, whose system absolutely rejects all such retrospective punishment, either from the danger of giving too much scope to vindictive passion, or on some more abstract principle of justice. Those who may incline to admit that the moral competence of the sovereign power to secure itself by the punishment of a heinous offender, even without the previous warning of law, is not to be denied, except by reasoning, which would shake the foundation of his right to inflict punishment in ordinary cases, will still be sensible of the mischief which any departure from stable rules, under the influence of the most public-spirited zeal, is likely to produce. The attainder of Strafford could not be justifiable, unless it were necessary; nor necessary, if a lighter penalty would have been sufficient for the public security.