The Civil Procedure Rules ( CPR) provides the relevant principles which govern the requirement for expert evidence.
CPR 1.1 refers to the overriding objective of “enabling the court to deal with cases justly and at proportionate cost”.
CPR 1.2 requires the court to seek to give effect to the overriding objective when it exercises any power given to it by the CPR. The parties to proceedings also have a duty to help the court to further the overriding objective (CPR 1.3).
In relation to expert evidence any practitioner is required to know that the starting point is CPR 35.1, which requires expert evidence to be restricted to what is “reasonably required to resolve the proceedings”.
The judgment link below identifies the principles to be determined when deciding whether expert evidence should be admitted, in particular it sets out the questions that are required to be addressed by the court, and gives an indication of the factors that will be required to support any application to introduce expert evidence.