Dineley was heard as a companion case alongside R. v. St Onge Lamoureux and involved an analysis of whether legislative amendments to Canada’s impaired driving laws could operate retrospectively, thereby preventing the accused from calling an expert witness to cast doubt on Breathalyzer results. The amendments in question only became law during the course of Mr. Dineley’s trial.
Some of the legislative amendments in question had been declared unconstitutional in St-Onge Lamoureux, while others limiting the evidence that an accused could call to cast doubt upon Breathalyzer results had been upheld. The question was whether these constitutionally valid amendments were merely procedural (in which case they could be applied retrospectively) or substantive (in which case only prospective application would be allowed).
The trial judge, and later the summary conviction appeal court, found that the amendments had a substantive effect on the defence of the accused and therefore allowed him to call the Breathalyzer results into question as had previously been allowed. The end result of Mr. Dineley’s trial was an acquittal.
The Ontario Court of Appeal, however, came to a different conclusion, finding that the legislative amendments were merely procedural in nature and could operate retrospectively, and on this basis ordered a new trial.
The Supreme Court of Canada overturned the Court of Appeal’s decision, noting that insofar as a legislative amendment affected an accused person’s right to utilize a defence, it is substantial and therefore cannot be applied retrospectively:
Unlike MacPherson J.A., I must conclude that the Carter defence has been eliminated as an independent means to raise a reasonable doubt about the reliability of breathalyzer test results. This, in my view, indicates that the provisions are not merely procedural; they affect a defence open to an accused and are therefore subject to the presumption against the retrospective application of new legislation. I agree with Mayrand J.A. in R. v. Gervais (1978), 43 C.C.C. (2d) 533 (Que. C.A.), that the right of an accused to rely on a defence is a substantive right and that new legislation has to be interpreted so as not to deprive the accused of a defence that would have been open to him or her at the time of the impugned act (p. 535).
In addition, Deschamps J., writing on behalf of the majority, concluded that the elimination of the Carter defence affected the presumption of innocence and was only saved as a “reasonable limit” under Section 1 of the Charter of Rights and Freedoms. Any legislative amendment that engages Charter rights, Deschamps explained, is by its very nature substantive, even if it is ultimately found to be constitutional under Section 1.
Based on these reasons, it was found that the amendments to Section 258(1)(c) of the Criminal Code could not be applied retroactively and that Mr. Dineley’s acquittal should therefore stand.