Derecho privado
Private law units such as companies or foundations can be used as well. Some countries, so as Germany, allow the municipals the ownership of private companies only if the purpose of the company is an economical not a public service. The easiest way to form a company by private law is the private limited company. It is easy and fast to found and the liability is limited to the assets of the company. However, while research shows such cooperation can be effective and efficient, the complexity of contracts in such arrangements can also lead to high failure rates.