Definitions of on the merits
if a judge decides a case on the merits (or on its merits) then he or she bases the decision on the substantive issues raised by the case and is not concerned by any technical or procedural defences that may be argued
Philip Morris Brasil filed its appeal against the decision on the merits with the Court of Appeals.
a ruling on the merits of a particular claim, case, or point of law etc is a ruling that considers the value or validity of the claim or case etc
There has not yet been a ruling on the merits of either the plaintiffs' individual claims.