Is a statute that will operate retroactively or retroactively?

Professor Driedger distinguishes between a statute which will operate retroactively and one which will operate retrospectively. In his text, Construction of Statutes (Second Edition, Butterworths 1983), he explains the distinction at p. 186: “A retroactive statute is one that operates backwards, that is to say, it is operative as of a time prior to its enactment. It makes the law different from what it was during a period prior to its enactment. A statute is made retroactive in one of two ways; either it is stated that it shall be deemed to have come into force at a time prior to its enactment, or it is expressed to be operative with respect to past transactions as of a past time, as, for example, the Act of Indemnity considered in Phillips v. Eyre. A retroactive statute is easy to recognize, because there must be in it a provision that changes the law as of a time prior to its enactment. ... “A retrospective statute, on the other hand, changes the law only for the future, but it looks to the past and attaches new prejudicial consequences to a completed transaction. ... A retrospective statute operates as of a past time in the sense that it opens up a closed transaction and changes its consequences, although the change is effective only for the future. . . .