The official press release explains:
The Billboard Liberation Front (BLF) is honored to announce a new marketing partnership with Philip Morris (PM) that finally brings together the rugged sense of American independence with your most important choice as a consumer: your death. The message of “My Life. My Death. My Choice.” informs and empowers the consumer to choose, as their god given right, how they want to die. Philip Morris brings this message to the consumer to remind them that some rights are inalienable in life as they are in death.
Almost as good as the AT&T one.