In a community-based health care system, every possible treatment cannot be provided to everyone — any more than everyone can have everything in a tax-based or private insurance system. But there are criteria for determining what will be restricted, and how. In Germany, these principles are laid out in law: a service must be necessary in order to be covered by the statutory health insurance system. This criterion builds on the individual-patient perspective: patients have a right to care that is objectively necessary to cure their disease, prevent a disease from progressing, or ease their suffering. But the perspective of the community is also considered: the costs must be reasonable in relation to the potential benefit.