Religious influences on medieval civil law:The pacta sunt servanda principle in Byzantine and medieval Western law

The rule of the pacta sunt servanda meaning “agreements must be kept” implies that, when two parties willingly and knowingly enter into a contract, the terms of that contract should be upheld by both parties; it is binding. Parties are free to determine the content of their contracts themselves. In civil law, we call this freedom of contract, a fundamental principle in modern civil law. The core of modern European civil law – mainly property law and the law of obligations – is based on Roman law (apart from in England). Yet, the principle of pacta sunt servanda, which forms the cornerstone of modern contract law, does not derive from Roman law. So how and when did this legal principle, which is so fundamental today, originate? In this paper I will attempt to show how religious influences played a role in the creation and development of this principle in the Middle Ages. I will try to show how this principle was actually adopted and developed in Byzantium on the one hand and in Western medieval Europe on the other, with an emphasis on Byzantium