The word "writ" refers to a legal document issued by a court that commands someone to do something or gives them legal notice of a claim against them. Full definition
This happens about 1 - 2 % of the time, but probably in about half or more of writs of habeas corpus that are formally valid (most are defective because they are rarely prepared by lawyers or people who understand the law in an area that is quite technical in any case). (law.stackexchange.com)
These include petitions for writs of certiorari, responses, merits briefs, emergency applications and most other filings. (abajournal.com)
Her texts On Designing (1959) and On Weaving (1965), for instance, are to this day regarded at the level of holy writ in many art, design, and textile courses. (artsy.net)