In 1626 Hampden, along with Sir Thomas Darnell, Sir John Corbet, Sir Walter Erle, and Sir John Heveningham, were among 70 individuals, including his nephew, the politician John Hampden, who were imprisoned without trial for refusing to pay "forced loans", demanded by Charles I to fund the current war against Spain.
[1] Hampden and the other knights submitted a joint petition for habeas corpus to the Court of King's Bench, which agreed and ordered them to be brought before the court to clarify what law they had broken.
[2] Hampden's counsel in the case was the noted legal scholar John Selden.
The judges were unable to determine what law had been broken, and avoided the issue by denying bail on the grounds that as there were no charges, "the [prisoners] could not be freed, as the offence was probably too dangerous for public discussion".
[3] Despite the judges' refusal to release the prisoners, Charles decided not to pursue charges.