January 28, 1999 – The Center filed a petition to list the Sacramento Mountains checkerspot butterfly as endangered under the Endangered Species Act.
March 2001 – The Center filed a lawsuit against the U.S. Fish and Wildlife Service for failing to protect the checkerspot. After issuing a positive initial finding in 1999, the agency had refused to take further action and later issued a moratorium on new additions to the endangered species list.
September 6, 2001 – In response to the Center's March 2001 lawsuit, the Service issued a proposed rule to list the checkerspot butterfly as endangered and proposed to designate the butterfly's entire habitat as critical habitat.
November 8, 2004 – The Service withdrew its 2001 listing proposal, claiming that threats to the species had been reduced.
October 2001 – The Center appealed a proposal to sell 80 acres of the Lincoln National Forest to the town of Cloudcroft on the grounds that the land was important habitat for the endangered checkerspot butterfly.
July 2, 2007 – The Center and Forest Guardians petitioned the Service a second time to protect the Sacramento Mountains checkerspot butterfly under the Endangered Species Act. The petition also requested emergency protection in response to a plan by Otero County to spray pesticides throughout the majority of the butterfly's private-lands habitat.
January 7, 2008 – The Center and Forest Guardians filed suit against the Service over the agency's failure to protect the Sacramento Mountains checkerspot butterfly.
April 15, 2008 – The Service and the Center reached a settlement requiring the agency to make a decision, by late November 2008, on our 2007 petition to list the Sacramento Mountains checkerspot butterfly under the Endangered Species Act.