Salus populi suprema lex esto - "The good of the people shall be the supreme law." Used variously as a motto, a reminder, or a notion of how the law and governments in general should be.⏎
Ultra posse nemo obligatur - "No one is obligated (to do) more than he can." Specifies that one should do what he can to support the community, but since everyone has different levels of ability, it cannot be expected that all will perform the same.⏎
Rex non potest peccare - "The king can do no wrong." Used to describe the basis for sovereign immunity.⏎
Sententia quae in rem iudicatam transit, pro veritate habetur - When a definitive sentence is declared, it is considered to be the truth. In the case of a sentence in rem iudicatam (that finally consents to consider a judgement completed), its content will then be the only legally relevant consideration of a fact.⏎
Solve et repete - Respect your obligation first, then you can ask for reimbursement. Used in those situations in which one of the two (or more) parties needs to complete his obligation before being allowed to ask for the opposite obligation to be respected by his counter party. Usually this principle is used in fields and subjects in which a certain general steadiness or uniformity of the system has been considered a relevant value by the legislator. The case is typical of service contracts with repeated obligations (like with gas, water, electricity providers and similars), in which irregularities on one side cannot be balanced if not in a regular situation (i.e., of payments) on the other side. The customer, for example, might be asked to pay regularly the new bill, before contesting the previous one in which he found irregular calculations, and asking for a balancement with newer bills; he thus cannot by himself determine a discount in the next payment.⏎