‘The borough courts, though, were busy with much more specific matters. Certainly, from the time of the Black Death between 1348 and 1349 and the Statute of Labourers in 1351, which attempted to control wages, local authorities regulated the price of all bread and ale that was sold. The courts used the law to enforce these regulations, and imposed their own systems of punishment (town courts could not outlaw criminals), which ranged from mutilation to forcing traders in bad goods to eat their produce in public, or have their bad drink poured over them. As with rural juries, maintaining the law was a matter of shame and reputation.
Haggling over basic commodities was illegal, and in most food markets bargaining was punishable by a fine and holding an auction was seen as a criminal act, held in secret. The ‘law of supply and demand’, that insists on higher prices when goods are in short supply, was regarded as anathema and therefore not allowed to operate in these medieval markets.
It can be argued that the true end of the Middle Ages came in the seventeenth century, when prices were allowed to rise in times of dearth, and the laws of supply and demand took over.’
– Jones. T., Ereira. A. 2004. Terry Jones’ Medieval Lives London, Great Britain: BBC Books (2005) p. 76