Canada's local court systems and procedural rules vary, especially at the lowest level, by province. So, I'm just stating some general principals.
General speaking legal arguments are limited to closing arguments of the parties after all of the evidence has been presented by both sides (because this limits legal arguments to those with evidentiary support rather than merely hypothetical arguments).
Opening arguments are usually supposed to be limited to a recitation of what the facts in the case will show. Presentation of evidence and examination of witnesses is also not a time for this to be done.
Some courts in some jurisdictions allow a defendant to make a "half-time motion" at the close of the prosecution's case, arguing that the prosecution has failed to meet their burden of proof to establish grounds for a conviction before the defense presents the defense's evidence. But, such formalities are often dispensed with in traffic court.
Some courts allow post-trial motions to be made after a verdict within a certain number of days set by court rule asking the court to reconsider its decision or overturn a jury verdict, although these aren't always available in a traffic court case.
Sometimes these issues are also raised in a pre-trial trial brief or in motion practice prior to trial.
The amount of time allowed for closing, and discretion to consider arguments at times other than time usually allowed are in the discretion of the trial judge.
Usually, courts are more lenient regarding formalities when a non-attorney is arguing a case.
Usually, there is less opportunity to raise legal arguments following a trial if the traffic court is not a court of record and appeal is by trial de novo in a higher court, and there is more opportunity to do so if the trial is in a "court of record" in which a transcript is maintained and if the trial is a jury trial (although in a jury trial, the legal arguments are made out of the presence of the jury in a hearing over jury instructions, rather than before the jury).
In a traffic case in a court of record, in front of a judge, five or ten minutes, at most, would be typical and trial briefs would rarely be considered, but the judge might listen longer or take the case under advisement and ask for further briefing, if the judge thinks that there is merit to a legal argument and wants to do further research (which would be extremely unusual in a traffic case).