I have sent the decision -- which I have in PDF and so it's not postable here -- around to friends who work for the Crown, who are defence lawyers and who sit on the bench.
Every single one of them agrees (not for attribution) that Ontario Court Justice Norris Weisman's decision will probably not stand.
[...]
On the one hand, although demeanour alone cannot be taken into account, the demeanour of a witness can be used in conjunction with the trier of fact's assessment of all the evidence and in the full context of the trial. This is especially the situation in sexual assault cases where the main issue is who is more credible: the Complainant or the Accused.
On the other hand, the complainant is asserting her freedom of religion charter rights to wear the niqab. In addition courts have said that witnesses (whether they are children or adults) can testify behind a screen or to wear a disguise where it is in the best interest of justice and that this does not offend an accused person's Charter right to a fair trial.
So there you have it.