The article focuses on writ of mandamus is appropriate in federal court and some of the exceptional cases for which writs of mandamus have been granted. It mentions issue of waiving venue in multidistrict litigation (MDL) court including the standard of evidence circuit courts have thus far employed in finding that venue has been waived. It also mentions how MDL defendants might rely on In re DePuy Orthopaedics as a template for obtaining favorable advisory opinions.