The Body of Canon law is historically continuous from the early church to the present, and such can claim to be the oldest functioning internal legal system in Western Europe, much later than Roman law but predating the evolution of modern European civil law traditions. Its institutions and concepts have influenced the secular law and jurisprudence in the modern state —e.g., marriage law, the law of obligations, the doctrine of modes of property acquisition, possession, wills, legal persons, the law of criminal procedure, and the law concerning proof or evidence. International law owes its very origin to canonists and theologians, and the modern idea of the state goes back to the ideas developed by medieval canonists regarding the constitution of the church.
It has, as a result of doctrinal and ecclesiastical schisms, developed differing, though often similar, patterns of codification and norms in the various churches that have incorporated it into their ecclesiastical frameworks. Canon law in the Western churches developed without interruption until the Reformation of the 16th century. Though other churches of the Reformation rejected the canon law of the Roman Catholic Church, the Church of England retained the concept of canon law and developed its own type, which has acceptance in the churches of the Anglican Communion. Canon law has functioned in the organization of the church’s liturgy, preaching, works of charity, and other activities through which Christianity was established and spread in the Mediterranean area and beyond. Canon law, moreover, had an essential role outside of the church in the transmission of Greek and Roman jurisprudence and in the reception of Justinian law in the 6th century (when the western part of the empire was in decline but the eastern Byzantine part was intact). Justinian Law hugely impacted Europe during the Middle Ages.
Because of a discontinuity, that has developed between church and state in modern there has been a contemporary crisis in canon law and a devaluing, even within much of the church . On a superficial level it can be seen as dead law (i.e., law no longer held valid) and say nothing about living law. However with a new climate of changing safeguarding expectations and rapidly changing expectations about the professional workplace, they maybe a need for canon law to becoming more assertive in balancing the rights of church ministers and the duty of care for these ministers by their own authorities. Their has been a growing number of religious workers looking for trade union membership to protect their interests, and because of a lack of confidence that due process and natural justice will be followed in a dangerous climate of a growing number of historical and false allegations.
Todays landmark revision by the Pope began a fourth period of canonical history which continues until the present day. Benedict XV, stated the reasons which prompted him as the supreme Pastor of souls, who has the care of all the churches, to provide for a new codification of ecclesiastic laws, with a view " to put together with order and clearness all the laws of the Church thus far issued, removing all those that would be recognized as abrogated or obsolete, adapting others to the necessities of the times, and enacting new ones in conformity with the present needs This new code, is sometimes referred to as the ius codicis ("law of the code") or, in comparison with all law before it, the ius novum ("new law"). From time to time, the Pontifical Council for Legislative Texts issues authentic interpretations regarding the code. The pope occasionally amends the text of the codes. Roman canon law is a fully developed legal system, with all the necessary elements: courts, lawyers, judges, a fully articulated legal code, principles of legal interpretation, and coercive penalties, though it lacks civilly-binding force in most secular jurisdictions. One example where conflict between secular and canon law occurred was in the English legal system, as well as systems, such as the U.S., that derived from it. Here criminals could apply for the benefit of clergy. Being in holy orders, or fraudulently claiming to be, meant that criminals could opt to be tried by ecclesiastical rather than secular courts. The ecclesiastical courts were generally more lenient. The benefit of clergy was systematically removed from English legal systems over the next 200 years and In English Law, the use of this mechanism, , was abolished by the Criminal Law Act 1827.