"Rights-based" community organizing, in which municipal governments are used to exercise community power, was first experimented with by the Community Environmental Legal Defense Fund (CELDF.org) in Pennsylvania, beginning in 2002. Community groups are organized to influence municipal governments to enact local ordinances. These ordinances challenge preemptive state and federal laws that forbid local governments from prohibiting corporate activities deemed harmful by community residents. The ordinances are drafted specifically to assert the rights of "human and natural communities," and include provisions that deny the legal concepts of "corporate personhood," and "corporate rights." Since 2006 they have been drafted to include the recognition of legally enforceable rights for "natural communities and ecosystems."