Rex non potest peccare - "The king can do no wrong." Used to describe the basis for sovereign immunity.⏎
Res inter alios acta vel iudicata, aliis nec nocet nec prodocet - What has been agreed/decided between people (a specific group) can neither benefit nor harm a third party (meaning: two or more people cannot agree amongst each other to establish an obligation for a third party who was not involved in the negotiation; furthermore, any benefit that may be established will have to be accepted by the third party before it can be implemented).⏎
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.⏎
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.⏎
Volenti non fit injuria - "Injury is not done to the willing." Notion that a person cannot bring a claim against another for injury, if said person willingly placed themselves in a situation where they knew injury could result.⏎