Mark Brookline is a staffer in the Communications Office during Jed Bartlet's first term. He, along with Steve Joyce, testified at Governmental Affairs that the White House could not produce the Rockland memo because they did not have the Rockland memo, which was a bald-faced lie. This upset White House Counsel Lionel Tribbey.
They were asked by Ainsley Hayes to take corrective steps to repair their mistake, but were quickly dismissed. After it was revealed that they sent Ainsley dead flowers with a note that read "bitch", they were both promptly fired by Sam Seaborn. Mark attempted to argue that Sam had no such authority, at which point Lionel and his cricket bat appeared to give weight to Sam's position.