Section 170A(1) of the CPA, properly construed in light of section 28(2) of the Constitution, requires that in every trial involving a child complainant in a sexual offence case, the court must enquire into the desirability of appointing an intermediary, even where the state does not raise the issue. The phrase 'undue mental stress or suffering' does not require a child to first be exposed to such stress; rather, the provision is designed to prevent such exposure. The discretion given to judicial officers whether to appoint an intermediary is not unconstitutional, as it allows for consideration of each child's individual circumstances and needs. Similarly, sections 153(3) and (5), 158(5), 164(1), and 170A(7) of the CPA, when properly interpreted in conformity with section 28(2), are not unconstitutional. Courts may raise constitutional issues of their own accord where the issue arises on the facts and is necessary for determination of the case, or where it is in the interests of justice to do so. However, the interests of justice will generally not require this Court to confirm orders of invalidity where the High Court improperly raised constitutional issues that had no bearing on the resolution of the cases before it.