According to CO 97 a debtor must pay compensation for damage resulting from the fact that he does not or cannot fulfil his agreed obligations at all or not properly, unless he proves that he is not at fault (exculpation, s. below).
The basis of a liability according to CO 97 is therefore an agreement or contract according to CO 1 («mutual expression of intent by the parties»). Consequently, if there is no contract between the person who caused the damage and the injured party, this type of liability cannot form the basis for a claim.
What is special about this type of liability is that the law assumes fault in a case of CO 97. However, the responsible person can try to prove the contrary by proving that he or shie is not at fault (exculpation, discharge of guilt).