• The presumption in both criminal and civil trials is that all witnesses are competent and compellable, so a reason in statute or case precedent has to be found to apply an exception.

• The main criminal law exceptions in relation to competence are defendants testifying for the prosecution, or witnesses who are unable to give intelligible testimony.

• The main criminal law exceptions in relation to universal compellability are defendants themselves and spouses (or civil partners) and co-defendants testifying for the prosecution.

• The general expectation is that witnesses will give evidence on oath (sworn evidence).

• In criminal cases witnesses under the age of 14 years cannot give sworn evidence.

• In civil cases a child (a person under the age of 18 years) who understands the nature of the oath must give sworn testimony, while others may give unsworn evidence under certain conditions.

• Special measures for vulnerable witnesses in criminal trials are directed primarily at non-defendants but there are some limited protections for some defendants.