Shark was in jeopardy of getting cancelled before it even started, but James Woods gave the legal drama new life, once he signed on to star in the pilot. Woods has spent most of his career focusing on feature films, not television. He said about the decision though, he had nothing against television as most people assumed, as he had done television movies. There were simply no characters, to which he was willing to commit, full-time, until the part of Sebastian Stark came along. The creator was looking for somebody like him to play the part anyway.
Stark has three rules, to which he refers as his "Cutthroat Manifesto": * "Trial is war. Second place is death." * "Truth is relative. Pick one that works." * "In a jury trial, there are only twelve opinions that matter, and yours (speaking to his team) is not one of them."
When Sam Page (Casey Woodland) decided not to come back to the series, the departure of his character was explained by saying that Casey was helping his father, who is a U.S. Senator, work on his election campaign, though it's not explained for what his father is running.
The absence of Jeri Ryan (Jessica Devlin) from the season two episodes that were shot and aired after the 2007-2008 writers' strike is explained by saying that she is in Chicago caring for her ailing father.
In the pilot, Claire Stark was portrayed by Lindsay Frost, when the character returned for a more permanent role in season two, she was replaced by Orla Brady. In the process, her character went from being American to an Irish-born U.S. citizen.