In an attempt to prevent Long's return to Parliament in 1628, the crown picked him as High Sheriff of Wiltshire, but nevertheless he managed to secure a seat for Bath in Somerset, arguing on tentative legal grounds that since the constituency lay outside his county, he was not breaking the law.
His continuing opposition to Buckingham finally resulted in his prosecution in October 1628 in a Star Chamber suit, and it was argued that Long had not only acted unlawfully in securing his election but also neglected his duties as Sheriff of Wiltshire.
In the tumultuous scenes on 2 March, he took a leading part when the Speaker, John Finch, was forcibly held down in his chair, preventing adjournment of the House.
Together with six others, he was arrested for offences committed within the House and appeared before the King's Bench, while simultaneously facing ongoing Star Chamber proceedings concerning his shrievalty.
However he was exempted from the Royal Pardon in November the following year because of his continuing opposition to the court, and particularly the writ of ship money.
Long took an active part in Parliament's cause during the civil war and after being severely wounded at the Battle of Edgehill, he raised a troop of horse and helped to organise Parliamentary forces in Wiltshire and Shropshire.