One of the reasons Parliament survived as an institution is
because the Commons normally did consent to raising 
taxation. But there were occasions when they said no - 
normally when the taxes were required to support an 
unpopular war. 

In 1376, military failures abroad combined with court 
scandals and the King's descent into feeble old age to set the 
country against him. As a result, the so-called Good Parliament 
not only refused taxation, it also took measures against corruption at court - especially against the King's mistress, Alice Perrers. In doing so, it created the process called impeachment - whereby the Commons as a body became able to prosecute offenders before the Lords - and set an important precedent for future opposition against the Crown.