Non faciat malum, ut inde veniat bonum - "Not to do evil that good may come." Performing some illegal action is not excused by the fact that a positive result came therefrom. Often used to argue that some forms of expression, such as graffiti or pornographic films, cannot be given the protection of law (e.g. copyright) as they are or may be considered illegal or morally reprehensible.⏎
Nulla poena sine lege or nullum crimen, nulla poena sine praevia lege poenali - "No penalty without law" or "no crime, no punishment without a previous penal law". (1) One cannot be prosecuted for doing something that is not prohibited by law. (2) One cannot be prosecuted for doing something that was not prohibited by law at the time and place it was committed, notwithstanding laws made since that time. A form of prohibition on retroactive laws.⏎
Nullum crimen, nulla poena sine praevia lege poenali - There can be neither crime nor punishment unless there is a penal law first.⏎
Qui facit per alium facit per se - "Who acts through another, acts himself." One who delegates a task to another, takes full responsibility for the performance of that act as if he himself had done it. Basis for the law of agency.⏎
Probatio vincit praesumptionem - Proof overcomes presumption.⏎