Engrossing, forestalling and regrating were marketing offences in English, Welsh and Irish common law.

The terms were used to describe unacceptable methods of influencing the market, sometimes by creating a local monopoly for a certain good, usually food.

[1] Blackstone's Commentaries described them as offences against public trade: Forestalling—the buying or contracting for any merchandise or victual coming in the way of the market; or dissuading persons from bringing their goods or provisions there; or persuading them to enhance the price, when there; any of which practices make the market dearer to the fair trader.

This must of course be injurious to the public, by putting it in the power of one or two rich men to raise the price of provisions at their own discretion.

The Domesday Book recorded that "foresteel" (i.e. forestalling, the practice of buying up goods before they reach market and then inflating the prices) was one of three forfeitures that King Edward the Confessor could carry out through England.

In the laws of Henry I of England forestalling was the crime of assault on the highway, an offence against the King's Peace.

The act excluded from the penalties it imposed the purchase and sale "in open Fair or Market" of "corn, Fish, Butter or Cheese, by any such badger, Lader, Kidder, or Carrier" as was granted a licence by three justices of the peace from the county in which he dwelt.

In addition to buy corn or grain out of market or fair to sell again, the licence had to contain "express words" allowing this.

The stringent technical requirements suggest that the legislature were concerned not only that markets were being threatened by competition from unregulated traders but also that licences were too freely available, either legitimately because the justices did not know how many were being granted, but also that they were being obtained illegally, perhaps from corrupt court officials or counterfeiters.

Although badgers, in common with most travellers in medieval and Elizabethan times, were required to have a licence, and presumably carried it with them and produced it if challenged.

Rusby was heavily fined, but, on appeal, the court was equally divided as to whether engrossing, forestalling and regrating were still offences at common law.