Kontraktuell lojalitetsplikt

Sammanfattning: This thesis addresses the emergence and position of a duty of loyalty in Swedish law after the execution of a contract. According to Swedish law, a party to a contract may have a duty to take reasonable care of the counterparty’s interests, a duty of loyalty (lojalitetsplikt). Even if the existence of such a duty is incontestable, the reasons for the emergence are quite unclear. Also, it has been unclear whether it has general applicability in the law of contracts, or if it is limited to some types of contract.The Supreme Court has only on a few occasions found behaviour to be loyal or disloyal, sometimes also invoking a duty of loyalty. In scholarly writing, however, the use of the concept of the duty of loyalty has become very popular, and the legislator often refers to the duty of loyalty as a basic principle in the laws of contract and obligations.Depending on how the content of a concept of a duty of loyalty is defined, Swedish law may be seen as including such a duty at least since the emergence of laws governing employment and fiduciary agents. There are signs of an even broader scope of application of a duty of loyalty beyond employment law and fiduciary duties, covering the law of obligations as a whole, or even private law in its entirety. The origins in central Swedish contract law as to the duty of loyalty occurred sometime in the 1970’s, followed by an expansion in contract law that accelerated in the 1990’s and has not slowed since. This development was initiated by the legislator in the mid-1970’s and received scholarly support in the mid-1980’s.The duty of loyalty is defined in Nordic law as a duty to effectuate or observe the other party’s interests (with care). The duty of loyalty means that the contract is to be applied loyally. In this lies a duty to interpret and perform the contract loyally; this often arises in that a party can have obligations entailing an effectuation of the opposing party’s interests despite the fact that these obligations are perhaps not explicit in the contract. A requirement of loyalty as a concept is used in this thesis that is prioritized over the duty of loyalty. The requirement of loyalty covers the duty of loyalty, a prohibition against the abuse of rights and a requirement of fairness.The thesis concludes that the duty of loyalty during the most recent 30 years has been sharpened and expanded.