How did Sir Edward Coke use medieval legal precedents to defend common law?

Sir Edward Coke was a pivotal figure in English legal history who defended the supremacy of common law by strategically interpreting medieval history to suit 17th-century constitutional needs.1

Rather than acting as an objective historian, Coke approached medieval sources—such as the Year Books—through the lens of a Tudor-era lawyer. He effectively "manipulated" these medieval precedents to construct a framework that challenged the Stuart monarchy's claims of absolute royal prerogative.1

Key methods he used to defend common law included:

• Systematizing Legal Principles: Through his influential Reports, he compiled and commented on judicial decisions, establishing them as the primary source for legal citation and creating a cohesive body of common law.21
• Drafting Constitutional Documents: He fashioned the Petition of Right (1628) by drawing upon ancient precursors, most notably the Magna Carta, to assert that the monarch could not levy taxes or imprison subjects without legal cause.13
• Judicial Advocacy: As a judge, he argued that the common law was the supreme authority, famously asserting that the king could not change the law by proclamation or adjudge cases in his own person.1