The Broad Seal War was a controversy over the results of a Congressional election in the U.S. state of New Jersey in 1838.
Following the closely contested election of 1838, two groups sought admission to the United States Congress from New Jersey. Both held commissions bearing the great (broad) seal of the state; only the Whig commissions, however, were legally executed and signed by the Governor of New Jersey, William Pennington. Charging their opponents with election fraud and facing loss of control of the House, the Democratic Party majority refused to seat all but one Whig. When it was proved that the county clerks in Cumberland and Middlesex counties had suppressed the returns in certain townships that would have given the Democrats a majority, the House, on February 28, 1840, seated the five Democratic claimants.