| 
    
     Köln, Erzbischöfliche Diözesan- und Dombibliothek 127, fol. 10v  | 
  
| Gratian,  Decretum, 
    D.4 d.p.c3:  Leges instituuntur cum promulgantur, firmantur cum moribus 
    utentium approbantur.  (Laws are 
    established when they are promulgated and confirmed when they are approved 
    by the long standing customs of those who obey them). Justinian, Institutes 1.2.9: Nam diuturni mores consensu utentium comprobari legem imitantur (cf. Gratian, Decretum, D.12 c.6) Consuetudo (Costume) Mos (?)  |