where there is a lis to be adjudicated upon, Cross-examination is a powerful weapon for showing the untruthfulness of an evidence,
98: … The principle that witnesses must be confronted and offered for cross-examination applies generally to proceedings in which witnesses are examined or documents are adduced in evidence in order to prove a point. Cross-examination then becomes a powerful weapon for showing the untruthfulness of that evidence. In proceedings before the Advisory Board, the question for consideration of the Board is not whether the detenu is guilty of any charge but whether there is sufficient cause for the detention of the person concerned. The detention, it must be remembered, is based not on facts proved either by applying the test of preponderance of probabilities or of reasonable doubt. The detention is based on the subjective satisfaction of the detaining authority that it is necessary to detain a particular person in order to prevent him from acting in a manner prejudicial to certain stated objects. The proceeding of the Advisory Board has therefore to be structured differently from the proceeding of judicial or quasi-judicial tribunals, before which there is a lis to adjudicate upon.
A.K. Roy V/s Union of India (1982) 1 SCC 271