The foregoing distinctions support the doctrines that have been established with reference to the legislative enactment of declaratory and retroactive statutes.

Declaratory statutes, that is, those legislative pronouncements as to how certain laws, previously established, are to be interpreted in courts and by executive agents, are valid only in so far as they are designed to govern future action. Cooley states the law upon this point as follows: "If the legislature would prescribe a different rule for the future from that which the courts enforce, it must be done by statute, and can not be done by a mandate to the courts which leaves the law unchanged, but seeks to compel the courts to construe and apply it not according to the judicial, but according to the legislative judgment "But in any case the substance of the legislative action should be regarded rather than the form; and if it appears to be the intention to establish by declaratory statute a rule of conduct for the future, the courts should accept and act upon it, without too nicely inquiring whether the mode by which the new rule is established is or is not the best, most decorous and suitable that could have been adopted." 12

"If," continues Cooley, "the legislature can not thus indirectly control the action of the courts, by requiring of them a construction of the law according to its own views, it is very plain it can not do so directly, by setting aside their judgments, compelling them to grant new trials, ordering the discharge of offenders, or directing what particular steps shall be taken in the progress of a judicial inquiry."

Retroactive legislation which does not impair vested rights, or violate express constitutional prohibitions, is valid, and, therefore, particular legal remedies, and, to a certain extent, rules of evidence, may be changed and, as changed, made applicable to past transactions, for it is held that, so long as the general requirements of due process of law are satisfied, no person has a vested right in any particular 1egal remedy or mode of judical procedure.

12 Constitutional Limitations, 7th ed., p. 137.

Again, in certain cases, the legislature is competent to validate proceedings otherwise invalid because of formal irregularities. But substantial rights may not thus be interfered with. To quote again from Cooley: "The legislature does, or may, prescribe the rules under which the judicial power is exercised by the courts; and in doing so it may dispense with any of those formalities which are not essential to the jurisdiction of the court; and whatever it may dispense with by statute anterior to the proceedings, we believe it may also dispense with by statute after the proceedings have been taken, if the court has failed to observe any of those formalities. But it would not be competent for the legislature to authorize a court to proceed, and adjudicate upon the rights of parties, without giving them an opportunity to be heard before it; and, for the same reason it would be incompetent for it, by retrospective legislation, to make valid any proceedings which had been had in the courts, but which were void for want of jurisdiction over the parties." 13

In Mitchell v. Clark14 was involved the constitutionality of a statute of 1863, by which Congress had declared: "That any order of the President, or under his authority, made at any time during the existence of the present rebellion, shall be a defense in all courts to any action or prosecution, civil or criminal, pending or to be commenced, for any such seizure, arrest or imprisonment, made, done or committed, or acts omitted to be done under and by virtue of such order, or under color of any law of Congress, and such defense may he made by special ,plea or under the general issue;" and "That no suit or prosecution, civil or criminal, shall be maintained for any arrest or imprisonment made, or other trespass or wrongs done or committed, or act omitted to be done, at any time during the present rebellion by virtue or under color of any authority derived from or exercised by or under the President of the United States, or by or under any act of Congress unless the same shall be commenced within two years next after such arrest, imprisonment, trespass or wrong may have been done or committed, or act may have been omitted to be done."

13 Op. cit. 150.

14 110 U. S. 633; 4 Sup. Ct. Rep. 170; 28 L. ed. 279.

Notwithstanding the very broad language of this act of immunity, the constitutionality of the measure was sustained. The court was, however, careful, in its opinion, to restrict its operation to the validation only of acts that it might have been possible for the President or Congress to have authorized at the time they were committed. Thus the opinion declares: "That an act passed after the event, which in effect ratifines what has been done and declares that no suit shall be sustained against the party acting under color of authority, is valid, so far as Congress could have conferred such authority before, admits of no reasonable doubt. These are ordinary acts of indemnity passed by all governments when the occasion requires."