The distinction has often been made between instances where the court has no jurisdiction whatsoever over the pending case and instances where the court has jurisdiction over the pending case, but is about to do some act, in the course of the trial, that it has no power to do. There is a distinction between no jurisdiction and an act in excess of jurisdiction. In either situation prohibition will issue.
J. P. McBaine,
Extraordinary Writ of Prohibition in Missouri, The (continued),
31 Bulletin Law Series.
Available at: http://scholarship.law.missouri.edu/ls/vol31/iss1/3