Statutory retroactivity

As a general rule for the interpretation of statutes, it may be laid down, that they never should be allowed a retroactive operation where this is not required by express command or by necessary and unavoidable implication. Without such command or implication they speak and operate upon the future only. Especially should this rule of interpretation prevail, where the effect and operation of a law are designed, apart from the intrinsic merits of the rights of parties, to restrict the assertion of those rights.