The general contract law principle of loyalty between negotiators, in deliberation, leads to a duty of disclosure for negotiators. The extent of this duty of disclosure is influenced by many different factors; amongst others the type of agreement, the negotiators knowledge and opportunity of procuring knowledge. The general duty of disclosure is both a part of the contract law principle of loyalty between negotiators in negotiating a contract, and an indirectly statutory obligation, that, if neglected will lead to Nullification of the agreement. The legislator has stated that the general contract law, Lag (1915:218) om avtal och andra rättshandlingar på förmögenhetsrättens område (avtalslagen), should be used to regulate negotiating of contracts, including the negotiation of contracts of employment. In arbetsdomstolens judging, additional factors have been weighed in, and the judgement is done also through the use of a concept taken from employment law, the concept of ?saklig grund för uppsägning?.