The issue focused on federal criminal laws that criminalize sexual activity between adults of the same gender. According to the Supreme Court, federal laws criminalizing sexual activity between adults of the same gender criminalize conduct that is lawful "only when it is unlawful for one sex to engage in it." Justice Anthony Kennedy wrote that "to criminalize conduct that is lawful only when it is unlawful for one sex to engage in it is to criminalize conduct that is lawful only when it is unlawful for one sex to engage in it."