The Broad Seal War was a constitutional and political controversy in the 26th United States Congress (1839–41) arising from the disputed results of the 1838 United States House of Representatives elections in the state of New Jersey, which would determine control of the House. The dispute was ultimately resolved in favor of the Democratic Party on February 28, 1840. The "war" is named for the "broad seal" of the state, which both delegations claimed to rightfully possess on their respective commissions of office.
Following the close elections of 1838, two contested contingents of the six New Jersey representatives-elect arrived at the House of Representatives on the opening day of the 26th United States Congress, requesting to be seated as members. While both held commissions bearing the great (broad) seal of the state, the Whig commissions were executed and signed by the Governor of New Jersey, William Pennington, while the Democratic commissions were signed by Secretary of State James Westcott. Clerk of the House of Representatives Hugh Garland refused to call the roll for the New Jersey delegation, citing the dispute and throwing the narrowly divided House into chaos.
After a lengthy dispute which delayed the election of a Speaker by more than two weeks, the House officially seated the five Democratic claimants on February 28, 1840, ruling narrowly that the clerks in Cumberland and Middlesex counties had suppressed the returns in certain towns that would have given the Democrats the majority.