Criminal Records. R v Pascal
In R v Pascal (Ont CA, 2020) the Court of Appeal summarizes the cross-examination that a witness may be subjected to regarding their criminal records and related behaviour:
 Section 12(1) of the Canada Evidence Act, R.S.C., 1985, c. C-5, permits questioning a witness on whether they have been convicted of any offence. The fact that a witness has been convicted of a crime is relevant to that person’s trustworthiness as a witness. Some convictions – for example, offences involving dishonesty or false statements – have a greater bearing on testimonial trustworthiness than others. The probative value of prior convictions also varies with other factors. The number of prior convictions. Their proximity or remoteness at the time of the witness’ testimony. See e.g. R. v. Brown (1978), 1978 CanLII 2396 (ON CA), 38 C.C.C. (2d) 339 (Ont. C.A.), at p. 342; R. v. Murray (1997), 1997 CanLII 1090 (ON CA), 115 C.C.C. (3d) 225 (Ont. C.A.), at para. 9.
 As a general rule, an ordinary witness, unlike an accused, may be cross-examined on unrelated misconduct which has not resulted in a criminal conviction. This includes cross-examination on conduct that underlies charges outstanding against a witness at the time of their testimony. The purpose of this cross-examination is to impeach the witness’ credibility: R. v. Davison, DeRosie and MacArthur (1974), 1974 CanLII 787 (ON CA), 20 C.C.C. (2d) 424 (Ont. C.A.), at pp. 443-44, leave to appeal refused,  S.C.R. viii; R. v. Gonzague (1983), 1983 CanLII 3541 (ON CA), 4 C.C.C. (3d) 505 (Ont. C.A.), pp. 510-11; and R. v. Gassyt (1998), 1998 CanLII 5976 (ON CA), 127 C.C.C. (3d) 546 (Ont. C.A.), at para. 37, leave to appeal refused,  2 S.C.R. vi.
 As a general rule, the mere fact that a witness is charged with an offence cannot degrade the witness’ character or impair their credibility. Generally this rule would mean that a witness could not be cross-examined about whether they were then charged with a criminal offence. But this rule gives way and permits cross-examination for the purpose of showing that the witness has a possible motivation to seek favour with the prosecution. A circumstance that may permit cross-examination on the fact of outstanding charges arises when the same police service that laid the charges outstanding against the witness also laid the charges against the accused about which the witness testifies for the Crown: Gonzague, at p. 511; Gassyt, at paras. 36-38; and R. v. Titus, 1983 CanLII 49 (SCC),  1 S.C.R. 259, at p. 263.