Leges humanae nascuntur, vivunt, moriuntur - "The laws of man are born, live, and die." Illustrates that laws are made, are in force for a period, and then become obsolete.⏎
Lex retro non agit - "The law does not operate retroactively." A law cannot make something illegal that was legal at the time it was performed. See ex post facto law.⏎
Lex posterior derogat priori - "Later law removes the earlier." More recent law overrules older ones on the same matter.⏎
Nemo judex in sua causa - "No one shall be a judge in his own case." Prevents conflict of interest in courts. Often invoked when there is really no conflict, but when there is even the appearance of one.⏎