"But defense counsel has no comparable obligation to ascertain or present the truth," White continued.
The problem is that in most fields, these are hard to ascertain unless you're pretty prominent.
Tan had been trying to ascertain the names of the more than 5,000 schoolchildren who died in the 2008 Sichuan earthquake.
early 15c., "to inform, to give assurance," from Anglo-French acerteiner, Old French acertener "to assure, certify" (13c.), from a "to" (see ad-) + certain "certain" (see certain). Modern meaning of "find out for sure by experiment or investigation" is first attested 1794. Related: Ascertained; ascertaining.