[1] He was one of the most influential and active figures in the Irish House of Commons during his lifetime, and was among the earliest eighteenth-century advocates of a union between England and Ireland.
Initially intending to pursue a career in law, he entered the Middle Temple in London in 1693, but left without being called to the bar.
[3] By 1704, Maxwell had become established as a core member of the Whig faction of Alan Brodrick in opposition to the administration of James Butler, 2nd Duke of Ormonde.
In 1711, a pamphlet, Anguis in herba, attributed to Maxwell, criticised peace negotiations aimed at ending the War of the Spanish Succession.
[4] Maxwell played a prominent role in the parliament of 1713 to 1714; at the start of the session, he led criticism of the Peace of Utrecht proposed by the British Tory leader, Robert Harley.
[1] In arguing for the bank, he acknowledged Ireland's subordination to the Kingdom of Great Britain and made a plea that his fellow countrymen take a similarly realistic attitude.
[2] Later in the same parliamentary session, he again led criticism of the Privy Council's tendency to amend Irish bills and denounced the practical operation of Poynings' Law.
Maxwell remained active in parliament throughout the 1720s; he was twice elected to the committee of public accounts (1721 and 1725) and played a central role in several legislative initiatives, in particular related to the linen industry.
As Maxwell died intestate and his three children, Robert, Edward, and Margaret, were still in their minority, Brice, as their next of kin, became their guardian and the administrator of the family estate.