Historical clue formulations

• Like the 18th Amendment, nowadays — 2026-09-05
• Invalid — 2024-03-22
• ___ and void — 2022-03-14
• ___ and void — 2021-12-15
• Zero — 2020-12-24
• Empty — 2020-04-17
• Of no value — 2019-06-07
• { }, in mathematics — 2016-10-01
• Invalid — 2015-07-02
• Empty — 2015-01-22
• Void — 2014-10-29
• Empty, as a math set — 2013-08-07
• Lacking value — 2012-10-31
• Empty, in math — 2011-03-30
• Zero — 2009-07-01
• ___ and void — 2009-04-06
• Invalid — 2005-10-23
• No longer legal — 2004-05-05
• Lacking any elements — 2003-07-19
• Without value — 2003-02-17
• Nonexistent — 2002-06-30
• Legally invalid — 2002-06-11
• Zero — 2002-01-20
• Aleph-___ — 2001-08-08
• Valueless — 2001-03-01
• Partner of void — 2000-08-07
• Zero — 2000-08-06
• Empty, in math — 1998-11-17
• Not valid — 1998-10-06
• Nonexistent — 1998-02-11
• Nonexistent — 1997-12-11
• Invalid — 1995-02-18
• Void's partner — 1995-02-07
• Void's partner — 1995-01-17
• Zero — 1994-07-10