Despite section 85 (4) (Inadmissibility of evidence from improper forensic procedures etc), evidence of how a forensic procedure was carried out is admissible in a proceeding against a person in a court—
(a) to establish or rebut an allegation that unreasonable force was used to enable the procedure to be carried out; or
(b) to decide the admissibility of a confession or admission or other evidence adverse to the person if the person alleges that the evidence was induced or obtained by the use of unreasonable force; or
(c) to establish or rebut an allegation that the forensic procedure was not carried out in accordance with part 2.6 (Carrying out forensic procedures).