The Airline Pilots' Association has taken High Court action against the Civil Aviation Authority's decision to seek pilots' conviction histories.
The CAA has already carried out one operation in which it accessed information held on pilots by the Ministry of Justice and had planned another such trawl in May.
Earlier this year, many members of the Pilots' Association had their records accessed without being notified, despite the ministry advising the CAA that those subject to such searches should be told.
The association's lawyer, Rodney Harrison, QC, told the High Court on Monday that if a pilot's medical condition changes between CAA inspections, they are required to release that information to the authority.
However, pilots are not under an obligation to release to the authority information regarding other matters.
Mr Harrison said the authority was unwilling to seek conviction material from pilots directly, but was misusing its legislation to gain that information from a third party.