The dictum made by Judge Wright in In re Athlumney ,  2 QB 547, p. 551-552, yet perfectly reflects the law against retrospective operation of law.The exact citation provided here proves the point clearly.
Perhaps no rule of construction is more firmly established than this: a retrospective effect should not be given to a statute so as to impair an existing right or obligation, except on procedural matters, unless the outcome can not be avoided without doing violence to the text. If the writing of the text may give rise to several interpretations, we must interpret it as having to take prospective effect only.
(See also Gustavson Drilling (1964) Ltd.. v. Minister of National Revenue , 1975 CanLII 4 (SCC) ,  1 SCR 271, p. 279.)
The presumption that the Oireachtas does not intend an Act to apply retrospectively was stated in Hamilton v Hamilton. Henchy J said:
"When an Act changes the substantive, as distinct from procedural law then, regardless of whether the Act is otherwise prospective or retrospective in its operation, it is not to be deemed to affect proceedings brought under the pre-Act law and pending at the date of the coming into operation of the Act, unless the Act expressly or by necessary intendment provides to the contrary."
Henchy J characterised the rule as a universal one, and emphasised that (contrary to the statement in Maxwell ) the rule applied to all pending enactments, unless the language irrefutably stated otherwise.[Statutory Drafting and Interpretation, Consultation Paper on: Plain Language and the Law (LRC CP14-1999)  IELRC 1 (1st July, 1999)