Yet, while the right of private property cannot be thus directly invaded, its security against the acts of the legislature is not as perfect as it might and ought to be made. The legislature must be allowed a large discretion in judging what is a public use: on that pretext much may be brought within its sweep unjustly, and the courts, in the absence of a constitutional rule, would be embarrassed in defining its limits. Experience has shown that much power to do wrong lurks under grants by no means essential to the public good. Besides what has been before referred to, the assumption of judicial functions by the Legislature and the broad field of Chancery jurisdiction over trust estates, which it has been held that they may exercise immediately, if they see fit, instead of vesting them in appropriate tribunals, are fraught with serious danger. The proneness of bodies so constituted to disembarrass themselves of the ordinary rules of evidence, to act upon _ex parte_ statements and testimony imperfectly authenticated, as well as the absence of all legal forms from their proceedings, and their numbers, among whom the responsibility of giving due attention to the case is divided, add to the peril. The power of legislating retrospectively has far too wide a scope; the constitutional inhibition of _ex post facto_ laws having been construed to apply to criminal or penal cases merely, restraining the legislature from making that an offence which was not so at the time of its commission, or increasing the punishment annexed to it. The course of legislation in this country amply demonstrates the wisdom, and even necessity, of extending the same prohibition to civil cases. There is no particular or partial inconvenience, which could outweigh the general benefits of a provision that no law, public or private, should operate retrospectively upon past acts; that the judgment of the tribunals upon every case should be according to the law as it was at the time of the transaction, which the parties were bound to know, and in accordance with which they are to be presumed to have acted.