Custom introduced against reason, ought rather to be called usurpation than custom.
Consuetudo debet esse certa; nam incerta, pro nullis habetur.
Custom ought to be certain; for if uncertain, it goes for nothing.
Consuetudo est bonus, rationabilis, certus et communis loci alicujus usus, cui memoria hominis non currat in contrarium.
Custom is the good, reasonable, certain, and common practice of any place, contrary to which nothing is in the recollection of man.
Consuetudo est optima interpres legum.
Custom is the best interpreter of the laws.
Consuetudo et communis assuetudo vincit legem non scriptam si sit specialis, et interpretatur legem scriptam, si lex sit generalis.
Custom and common practice overrules a law not written, if it be special, and interprets a written law, if the law be general.
Consuetudo ex certa causa rationabili usitata, privat communem legem.