The law was also challenged under the Equal Protection Clause. It was argued that it banned some semi-automatic weapons that were functional equivalents of exempted semi-automatic weapons and that to do so based upon a mix of other characteristics served no legitimate governmental interest. The reviewing court held that it was "entirely rational for Congress ... to choose to ban those weapons commonly used for criminal purposes and to exempt those weapons commonly used for recreational purposes".[23]:10[27] It also found that each characteristic served to make the weapon "potentially more dangerous", and were not "commonly used on weapons designed solely for hunting".[23]:10–11[28]