The line between principled but forceful political resistance and criminal disorder is ever a fine one. Regardless of legal definitions, in practice the distinctions are often blurred and perceptions of events and personalities can be tilted in either direction by political propaganda and public opinion. These factors were at work in England in the closing days of the Merciless Parliament when the Lords Appellant took steps to legitimise their actions, which in effect had included armed rebellion and usurping royal authority to judge and execute the king's subjects. On 2 June 1388, King Richard heard and granted a series of Commons petitions. These requested general pardons for the citizens of London and anyone else caught on the wrong side between 1386 and 1388; and a more specific undertaking that the Lords Appellant and those who had given them armed support would never in future be ‘accused, molested, or harmed for anything aforesaid, either at the suit of the king or that of any party’.

By including references to ‘assembly, expedition, combat, raising of pennants or banners’ and ‘coming and remaining with force and arms, or armed in the presence of the king’, as well as imprisonment and homicide, this last petition acknowledged that the Appellants had engaged in violent armed resistance that could in other circumstances be interpreted as treasonous rebellion. However, it carefully justified these actions by implicit reference to diffidatio. Diffidatio was the formal renunciation of liege homage, which meant breaking the oath of reciprocal trust and fidelity between a man and his lord. According to custom, in dire circumstances knights and noblemen had the right – even the duty – to renounce their fealty to a king who was ruling unjustly and providing bad lordship, and this right extended to defending the common good through armed resistance if necessary. When the 1388 petition framed the Appellants as having acted ‘to the honour of God, the salvation of the king … the maintenance of his crown and the salvation of all his kingdom’, it was this shared cultural understanding of knightly diffidatio that structured the request.