Accuracy is an issue that points to the reliability of language used in legal circles. The objective of the present study is to investigate linguistic devices denoting accuracy in Thai legal discourse. Data was gathered from judgments in three Thai courts: the Supreme Court, the Supreme Administrative Court and the Constitutional Court. Findings from Thai legal language were also compared to those from three registers: academic, media and political. The results show that Thai legal language employs two major linguistic devices in order to express accuracy: mention of the sources of evidence and legal citations. The use of the two devices is significantly present in legal language when compared with other registers.