December 10, 2002 – The Center and partners petitioned the U.S. Fish and Wildlife Service to emergency-list the island marble butterfly as an endangered species under the Endangered Species Act.
October 18, 2004 – The Center and partners sued the Service to force a response to its petition.
February 13, 2006 – The Service acknowledged that the Center's 2002 petition was warranted and began a status review of the island marble butterfly.
November 14, 2006 – After reviewing the status of the island marble butterfly, the Service finally denied the Center's 2002 petition to list the butterfly under the Endangered Species Act, concluding that the species did not require protection.