Untenable is defined as something that cannot be maintained or defended. If you have a weak argument that falls apart as soon as anyone expresses any skepticism, this is an example of when you have anuntenable argument. that cannot be held, defended, or maintained.
Eighteenth Amendment to the United States Constitution. The Eighteenth Amendment (Amendment XVIII) of the United States Constitution effectively established the prohibition of alcoholic beverages in the United States by declaring the production, transport, and sale of alcohol (though not the consumption or private possession) illegal.
The 18th Amendment and the Volstead Act. The Anti-Saloon league, through its allies in Congress, introduced the Prohibition Amendment in 1917. It was submitted to the House of Representatives on April 4, 1917. The Senate received the resolution on July 30, 1917 and passed it August 1 by a vote of 65 to 20.