
According to the Supreme Court - it depends: R v NS, 2012 SCC 72 [see previous post on NS by Dallas: Niqabs and the Criminal Justice System].
M---D S. & M---l S. were charged with sexually assaulting N.S. The parties were N.S.’ cousin and uncle, respectively. The Crown elected by indictment and a preliminary hearing commenced.
At the preliminary hearing the Crown sought to call N.S. as a witness. N.S., a Muslim, wished to testify while wearing her niqab. Both accused sought an order forcing her to remove her niqab when testifying so that they could they could effectively cross-examine her and so that the court could assess her demeanour. A voir dire was conducted.