<p>Language works by rules, yet linguistic rules may be intentionally and legitimately violated in certain areas of language use to achieve pragmatic purposes. This phenomenon, known as Special Language Domain (SLD), provides a unique perspective to unravel the motivation, mechanism, and limit of language evolution. This paper presents a mixed-method empirical study that investigates the grammaticality and acceptability of Chinese news headlines as a type of Special Language Domain. A total of 1422 participants provided introspective judgments by filling out a questionnaire, and semi-structured interviews were conducted with 12 participants. Linear mixed-effects models were used to analyze grammaticality and acceptability judgment data. The findings indicate that SLD constitutes a third category of linguistic forms distinct from grammatical and ungrammatical usages, which contributes to a comprehensive account of language performance. We substantiate linguistic argumentations with a gradience of grammaticality, strength, and limit of violations within SLD. Factors determining the acceptability of SLD are discussed, including intrinsic factors related to language and extrinsic factors related to language users, through the interaction between grammar and experience. These empirical results provide compelling evidence for linguistic theory and shed implications on the nature of grammaticality and acceptability.</p>