[5] Bradstreet entered the Irish House of Commons as Member of Parliament (MP) for Dublin City in 1776, representing the constituency until 1784,[7] when he was appointed Fourth Justice at the Court of King's Bench (Ireland).
Unlike many of his colleagues, he was able to work harmoniously with his Chief Justice, John Scott, 1st Earl of Clonmell, who called him "my assistant".
[9] He was a good and frequent speaker in Parliament: though loosely associated with the Irish Patriot Party he clashed on occasion with Henry Grattan, and claimed that the liberties granted by the Constitution of 1782 were insufficient.
[9] He prided himself on independence of mind; according to Ball his nickname "Slippery Sam" did not mean that he was corrupt or untrustworthy but rather that no party could ever count on his support.
[9] He was described as firm and decisive in character, rough in manner, and enormously fat (Chief Justice Scott, who was himself rather heavy, flippantly called him "the double man").