Had a long history of journalism, writing comic strips and short stories before pursuing a writing career.
Worked as a data entry clerk for the 1984 Summer Olympics, a typist for a temp agency, and an usher in a Westwood movie theater before his career took off.
His unproduced script Shadow Conspiracy, a Vietnam-set supernatural thriller, was partially responsible for his break in the 1980's as it landed him an agent and several script rewriting jobs for 20th Century Fox.
Co-starred as Hawkins, a member of Dutch's team, in 1987's Predator.
Made his directorial debut with the 2005 neo-noir crime comedy Kiss Kiss, Bang Bang.
Frequently uses Christmas as the backdrop in his scripts, including Lethal Weapon, The Long Kiss Goodnight, and Iron Man 3, and this was somewhat inspired by its use in the 1975 Sydney Pollack film Three Days of the Condor.