The law requires the parties to produce, before the Court, the best available evidence, the fact remains that even in a criminal trial, prosecution as well as defence has the right to choose their witness or witnesses and also as to what evidence they would adduce. Nonetheless, they are bound to adduce the best available evidence. The Court has no power to compel either the prosecution or the defence to examine any particular witness.
Examination of a witness by the adverse party is called the cross-examination. It is the most effective of all the means for extracting truth and exposing falsehood. It is a greatest legal engine ever invented for discovery of truth. It is the only mode to test the veracity of the statements given by a witness in examination-in-chief relating to an occurrence, which took place with him or in his presence. It is not an empty formality but a very valuable right, and a weapon in the armory of the adverse party to destroy the case of the opposite party and to substantiate his defence.
Personal magnetism is, perhaps, the most important of all the attributes of a good trial lawyer. Those who possess it never fully realize it themselves and only partially, perhaps, when under the influence of a large audience. There is nothing like an audience as a stimulant to every faculty. [Manual of Cross-Examination]