Forensic linguistics, legal linguistics, or language and the law is the application of linguistic knowledge, methods, and insights to the forensic context of law, language, crime investigation, trial, and judicial procedure. It is a branch of applied linguistics.

Forensic linguistics is an umbrella term covering many applications to legal contexts. These are often split between written and spoken items. It is common for forensic linguistics to refer only to written text, whereas anything involving samples of speech is known as forensic speech science.

There are principally three areas of application for linguists working on written texts in forensic contexts:

Forensic speech science also has many different applications:

The discipline of forensic linguistics is not homogeneous; it involves a range of experts and researchers in different areas of the field.

The term forensic linguistics first appeared in 1968 when Jan Svartvik, a Swedish professor of linguistics, used it in "The Evans Statements: A Case for Forensic Linguistics" an analysis of statements by Timothy John Evans. It was in regard to re-analyzing the statements given to police at Notting Hill police station, England, in the case of an alleged murder by Evans in 1949. Evans was suspected of murdering his wife and baby, and he was tried and hanged for the crime. Yet, when Svartvik studied the statements allegedly given by Evans, he found that there were different stylistic markers involved, and Evans did not actually give the statements to the police officers as had been stated at the trial. Sparked by this case, forensic linguists in the UK at the time were focused on questioning the validity of police interrogations. As seen in numerous famous cases (e.g. the convictions of Derek Bentley, the Guildford Four, the Bridgewater Three), many of the major concerns were of the statements police officers used. Numerous times, the topic of police register came up – the type of stylist language and vocabulary used by members of the law enforcement when transcribing witness statements.

In the US, forensic linguistics can be traced back as early as 1927 to a ransom note in Corning, New York. The Associated Press reported, "Duncan McLure, of Johnson City, uncle of the [kidnapped] girl, is the only member of the family to spell his name 'McLure' instead of 'McClure'. The letter he received, supposedly from the kidnappers, was addressed to him by the proper name, indicating that the writer was familiar with the difference in spelling." Other work of forensic linguistics in the United States concerned the rights of individuals with regard to understanding their Miranda rights during the interrogation process. The 1963 case of Ernesto Miranda was pivotal to the beginning of the forensic linguistics field. His case led to the creation of the Miranda rights and pushed the focus of forensic linguistics on witness questioning rather than police statements. Various cases came about that challenged whether or not suspects truly understood what their rights meant – leading to a distinction of coercive versus voluntary interrogations. An early application of forensic linguistics in the United States was related to the status of trademarks as words or phrases in the language. One of the bigger cases involved fast food giant McDonald's claiming that it had originated the process of attaching unprotected words to the "Mc" prefix (referred to as McWords) and was unhappy with Quality Inns International's intention of opening a chain of economy hotels to be called "McSleep".

In the 1980s, Australian linguists discussed the application of linguistics and sociolinguistics to legal issues. They discovered that a phrase such as "the same language" is open to interpretation. Aboriginal people have their own understanding of, relationship with, and use of "English" — something that is not always appreciated by speakers of the dominant version of English, i.e. "white English". The Aboriginal people also bring their own culturally-based interactional styles to the interview.