In legal context, merit (in singular form) or merits (in plural form) may have multiple meanings.

• Merit means a valid basis for a case or claim. For example, a legal action considered “without merit” is one that has no valid basis.
• Merit may also denote the strict rights of the parties to a legal case/ lawsuit.
• Merits are the substance of a legal dispute and not the technical grounds that may impact the outcome of a lawsuit.

A “judgment on the merits” is the final resolution issued for a particular dispute/ case.

A “defence upon the merits” (defence on the merits) is one that lays expectations on the justice of the cause, and not on technicalities only.