The 1883 health insurance law did not address the relationship between sickness funds and doctors. The funds had full authority to determine which doctors became participating doctors and to set the rules and conditions under which they did so. These rules and conditions were laid down in individual contracts. Doctors, who had grown increasingly dissatisfied with these contracts and their limited access to the practice of medicine with the sickness funds, mobilized and founded a professional association (Hartmannbund) in 1900 and even went on strike several times. In 1913 doctors and sickness funds established a system of collective bargaining to determine the distribution of licenses and doctors' remuneration. This approach is still practiced, although the system has undergone many modifications since 1913.