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.⏎
Sic utere tuo ut alienum non laedas - "Use your property so as not to injure that of your neighbours." While an individual is entitled to the use and enjoyment of one's estate, the right is not without limits. Restrictions can give rise to tort actions include trespass, negligence, strict liability, and nuisance.[8]⏎
Vigilantibus non dormientibus aequitas subvenit - "Equity aids the vigilant, not the sleeping." Concept that if an opposing party unreasonably delays bringing an action, that it is no longer considered just to hear their claim, due to fundamental changes in circumstance brought upon by their delay.⏎
Res ipsa loquitur - "The thing speaks for itself." Used in tort law when there is no proof of what caused the harm, but it is most likely only the thing that could have caused the harm.⏎