Henry II's control over vast territories in France had significant implications for his reign in England. These continental possessions demanded considerable attention, leading to frequent absences from England and a reliance on officials to manage domestic affairs. The need to defend these territories also resulted in heavy military expenditures and conflicts, notably with the French king. Furthermore, his holdings in France often embroiled him in European politics, which sometimes distracted from domestic governance. These factors created a complex dynamic in which Henry's continental ambitions and responsibilities influenced his administrative and diplomatic decisions in England.

The Assize of Clarendon, enacted in 1166, was a cornerstone of Henry II's legal reforms. It established procedures for criminal justice, notably the use of juries for the accusation of criminals. This assize marked a significant shift from trial by ordeal or combat to a more evidence-based judicial process. It enabled royal officials to oversee criminal proceedings, enhancing the crown's control over law enforcement. This system not only expanded the King's judicial authority but also contributed to the development of the English legal system, laying groundwork for due process and trial by jury.

Henry II's policies significantly impacted the feudal system in England. His reforms aimed at centralising power, which in turn diminished the autonomy of feudal lords. By asserting royal authority in legal matters and limiting the judicial powers of the barons, Henry effectively reduced their influence and control. His administrative reforms, such as the inquest system and efficient tax collection, further undermined the feudal lords' traditional roles and privileges. These changes shifted power from a decentralised feudal structure to a more centralised royal governance, reshaping the political landscape of medieval England.

Henry II's reign had a profound impact on the development of the English legal system. His establishment of Common Law and the introduction of legal reforms, such as circuit courts and trial by jury, were foundational in creating a unified legal framework. These reforms diminished the influence of feudal and ecclesiastical courts, centralising legal authority under the crown. The concept of a jury of peers and the establishment of legal precedents became integral aspects of English law. Henry's reforms laid the groundwork for a system based on common rules and procedures, shaping the evolution of English jurisprudence.

Henry II's conflict with Thomas Becket epitomised the tension between Church and State during his reign. This conflict stemmed from Henry's efforts to limit clerical privileges and assert royal authority over church matters. The pivotal moment was the Constitutions of Clarendon (1164), where Henry sought to reduce ecclesiastical courts' power and bring clergy under royal legal jurisdiction. Becket, the Archbishop of Canterbury, resisted these reforms, defending the Church's autonomy. Their conflict symbolised the broader struggle over whether secular or religious authorities held ultimate power, a key theme in medieval politics.