The doctorate is based on the question whether trade law and law of self-employment takes the increasing tendency into account that a person being the “archetype” of a trader and a self-employed person no longer practises his profession as an individual, but as “person in business” gives a partnership the feature of a company carrying on profession. Bearing this in mind the most important laws – from the author’s point of view - of trade law and professional law have been investigated – mainly in their personal field of application with a view to whether the trading partnership is exercising profession itself. If this is the case what requirements are there that have to be fulfilled by a person in a business of that kind. By comparing establishments of standards within each legal field discrepancies are uncovered between the laws and their interpretation of statutes by jurisdiction and jurisprudence. The author draws the conclusion that trade law makes a principle of permitting what has not been prohibited, that the commercial company and particularly trading partnership itself is professionally practising, not its partners. As far as self-employment is concerned things are different. Here the rule is that the commercial company in principle grants capable of exercising “the” independent profession on condition that the legislator has made it member of the circle of legal subjects through positive law.