While the All Writs Act is not used every day, the act has been successfully invoked by the government to compel telephone companies to install wiretaps, for phone companies to hand over call records, and to obtain CCTV footage, handwriting exemplars, and DNA samples. It has even been cited to force a defendant to cough up his computer password.
What’s more, it has played a part in copyright piracy cases. In a forthcoming law journal article,Annemarie Bridy, a law professor at the University of Idaho, writes that “some courts granting broad preliminary orders against non-parties in ‘pirate site’ cases have cited the All Writs Act as a source of authority.”
The All Writs Act was originally part of the Judiciary Act of 1789, which established the Supreme Court, the lower courts, and spelled out the basic powers of the judicial branch of government. In 1990, former Justice Sandra Day O’Connor described the Judiciary Act as “probably the most important and most satisfactory Act ever passed by Congress.”
Via How Apple will fight the DOJ in iPhone backdoor crypto case @ Ars Technica.