Prima facie (/ˌpraɪmə ˈfeɪʃi, -ʃə, -ʃiiː/; from Latin prīmā faciē) is a Latin expression meaning "at first sight",^[1] or "based on first impression".^[2] The literal translation would be "at first face" or "at first appearance", from the feminine forms of primus ("first") and facies ("face"), both in the ablative case. In modern, colloquial, and conversational English, a common translation would be "on the face of it".

The term prima facie is used in modern legal English (including both civil law and criminal law) to signify that upon initial examination, sufficient corroborating evidence appears to exist to support a case. In common law jurisdictions, a reference to prima facie evidence denotes evidence that, unless rebutted, would be sufficient to prove a particular proposition or fact.^[3] The term is used similarly in academic philosophy.^[2] Most legal proceedings, in most jurisdictions, require a prima facie case to exist, following which proceedings may then commence to test it, and create a ruling.^[3]

The similar ex facie, Latin for "on the face [of it]," is a legal term typically used to note that a document's explicit terms are defective without further investigation. For example, a contract between two parties would be void ex facie if, under a legal system where it was a binding requirement for validity, the document did not require party A to give consideration to party B for services rendered.