The control-flow of business workflows is characterized by the strict execution order of the activities that is already defined at design time. This well-structured control-flow is for instance absolutely necessary if the workflows have to be performed fully automatically. However, this rigidity is not always appropriate for people-oriented workflows. Especially in scenarios where real world processes are only semi-structured humans should have more freedom to decide in which order they want to perform the activities. In this paper, we suggest an approach to design peopleoriented workflows via constraints to make them more flexible.