In review we can say that within a comparatively broad field of the American law required joinder of claims is the rule. There are some exceptions. The German law has no rule of compulsory joinder of claims. Here, there are some exceptions, too. In this sense and within a field which is marked out by the American rule and the German exceptions, the relationship of rule and exceptions is reversed in the two systems.
Dieter L. Hoegen,
Required Joinder of Claims,
Mich. L. Rev.
Available at: https://repository.law.umich.edu/mlr/vol55/iss7/3