The former security was first created by the 1283 Statute of Merchants, or Statute of Acton Burnell (named after Acton Burnell in Shropshire, the place where Parliament met and passed the statute) and amplified by the 1285 Statute of Merchants 1285, whence its name, and the latter by an act of 1353, which provided that in every staple (i.e. public mart) the seal of the staple should be sufficient validity for a bond of record acknowledged and witnessed before the mayor of the staple. They were originally permitted only among traders, for the benefit of commerce, but afterwards extended by an act of Henry VIII (1532) to all subjects, whether traders or not. The creditor under either form of security was allowed to seize the goods and hold the lands of a defaulting debtor until satisfaction of his debt. While he held the lands he was termed tenant by statute merchant or by statute staple. In addition to the loss of his goods and lands the debtor was liable to be imprisoned. Statute merchant, owing to the summary method of enforcing payment, was sometimes known as pocket judgment. Both were repealed by the Statute Law Revision Act 1863.
An example of a suit of Statute Merchant can be seen in the Plea Rolls of the Court of Common Pleas, in 1430, where John Salter, citizen & tanner of York, John Wyot, vicar of St Nicholas, Mikelgate, John Yoman, (the latter 2 as executors of Henry Ravenswath) are parties. 
- Common Plea Rolls; National Archives; CP 40 / 677; http://aalt.law.uh.edu/AALT1/H6/CP40no677/aCP40no677fronts/IMG_0555.htm; last entry on image.