Omnis conclusio boni et veri judicii sequitur ex bonis et veris praemissis et dictis juratorem. Every conclusion of a good and true judgment¹ arises from good and true premises², and the sayings of jurors. Co. Litt. 226.

Omnis consensus³ t ollit errorem. Every consent removes error. 2 Inst. 123.

Omnis definitio in jure periculosa est; parum est enim ut non subverti posset. Every devinition in law is perilous⁴, and but a little may reverse it. Dig. 50, 17, 202.

Omnis exceptio est ipsa quoque regula. An exception is, in itself, a rule.

Omnis innovatio plus novitate perturbat quam utilitate prodest. Every innovation disturbs more by its novelty than it benefits by its utility.

Omnis interpretatio si fieri potest ita fienda est in instrumentis, ut omnes contrarietates amoveantur. The interpretation⁵ of insturments is to be made, if they will admit of it, so that all contradictions may be removed. Jenk. Cent. 96.

Omnis interpretatio vel declarat, vel extendit, vel restringit. Every interpretation either declares, extends or restrains.

Omnis regula suas patitur exceptiones. All rules of law are liable to exceptions.

Omnis privatio praesupponit habitum. Every privation presupposes former enjoyment⁶. Co. Litt. 339.

Omnis ratihabitio retro trahitur et mandato aequiparatur. Every consent given to what has already been done, has a retrospective effect and equals a command. Co. Litt. 207.

Once a fraud, always a fraud. 13 Vin. Ab. 539.

Once a mortgage always a mortgage.

Once a recompense always a recompense. 19 Vin. Ab. 277.

One should be just before he is generous.

One may not do an act to himself.

Oportet quod certa res deducatur in judicium. A thing, to be brought to judgment, must be certain or definite. Jenk. Cent. 84.

Oportet quod certa sit res venditur. A thing, to be sold, must be certain or definite.