Born in Hawaii, Poirier graduated from the University of Southern California with a Bachelor of Fine Arts in Drama, before attending UCLA's film school.
He began his career as a director in theater and worked in numerous playhouses including the Edinburgh Festival in Scotland.
In 1990, Poirier had his first screenplay, Danger Zone III, filmed. The action flick, which he co-wrote with Jason Williams (who wrote the first two Danger Zones), convinced him to try writing solo.
His next project, The Stranger, came out four years later. The action/western about a nameless woman who comes to town and beats up a gang of violent bikers was poorly received but did garner a best actress nomination from the Young Artist Awards.
That same year he joined forces with Jason Williams and came out with another action/western involving motorcycles, Death Riders.
By 1997, he dumped his action-western-bikers fascination and turned to drama.
About the injustice done to a town of African American people in Florida, the film won numerous awards including the prestigious Paul Selvin Award from the Writers Guild of America.
He followed that success with work on the popular sequel to Disney's The Lion King, The Lion King II: Simba's Pride. A film that went straight to video, it incorporated the ever-popular Romeo and Juliet story line.