Charles I undermined English common law by misusing the rhetoric of monarchical prerogative where custom or sometimes theology normally prevailed, thus calling into question the ‘ancient constitution’ and precipitating the Civil War.

Enshrined by common law, the ancient constitution preserved continuity, but had to account for the Saxon and Norman invasions. It defined the English realm, establishing a balance between prescriptive rights and royal prerogative, and separating England from written, promulgated Roman law. Common lawyers viewed the constitution as deeply historical, holding moral lessons; however, unlike French, Scottish, and Dutch constitutionalists who were more Protestant rebels than traditionalists, the English were evolutionary.

Aquinas had held some human laws are formal, demonstrative conclusions of natural laws, a conclusion shared by Christopher St German and Sir John Doddridge among others. Custom as law is acceptable so long as not contrary to natural law, a choice among possibilities left open, or reason applied to circumstance. ‘Artificial reason’ supports law as embodying rationality superior to positive rule (in a person), in that no one can claim higher authority; and unites custom and reason. Some Stuart thinkers emphasized more custom, some more reason. Either way, the artificial reason of lawyers largely consisted of discerning the rational core of custom.

There had never been an ancient constitution as it was in the 17th century, but its elements were demonstrable, as in John Selden’s identifying positive laws from Saxon times, land tenure after the Normal conquest, and legal officers over various dynasties had persisted in England. He assumed government was to serve its ends via accepted institutions, that long use made for the best fit – custom. Many common lawyers, notably Coke, were disquieted about changing laws, preferring to accept imperfection rather than introduce new defects, a residue of the Aristotelian view shared by Aquinas, Bodin, Machiavelli, Bacon. Custom did not have conservative overtones, however, for it was but a tool for explaining how positive law could be rational yet independent of any person or institution, drawn from natural reason alone. Common lawyers followed St German, active in the 1520s (save for Coke, who tended toward John Fortescue’s unchanging simplicity). Bacon did not go so far as Doddridge in uniting law and reason, but held common law contained laws of reason (i.e., nature), making it sufficient to rule out common law’s subordination to higher law or authorities (save common lawyers). The central tenets of Hooker’s ecclesiology, marked by Aristotelian possibilities actuating to identity, followed suit: custom provided rationality, change is best when evolutionary, circumspect of deliberate alteration, using articifical reason to elucidate matters.

During the first Stuart era, the rhetoric of the common law was one of three ‘master languages’ in England. The others were civil law, drawn from European politics and trade and focused on sovereignty (i.e., the monarch); and canon law or theology, originating in natural law but playing a lesser role following Henry VIII’s suppression of the monasteries. Civil law was associated with absolutism, though not only for ideological reasons, for it tended to compare itself to natural law be more highly abstract than common law. Whereas theology comprised statements of moral duty, based on theory of natural order and millenarian, and so tending to be politically unspecific. The working of these languages required users to know the time and place for employing idiom.

The problem of the right to resist in the ancient constitution required the king to be subject to common law, but not contract theory and natural rights; nor was it opposed to absolutism. In this era, monarchy was agreed to possess a ‘duplex’ character, comprising participation in the common law and simultaneously enjoying an ill-defined prerogative: the duplex conjoined the three languages. Common law was first among equals while civil law and theology were more attuned to prerogative. Hence the 17th-century elaboration of prerogative did not make it absolutist. James never asserted he could simply override the common law, even as king-in-parliament. But Charles misused the common-law rhetoric, causing distrust at the same time Laudian rhetoric was rising and the Calvinist declining. In the five Knights case, Attorney General Sir Robert Health argued the king could use prerogative to deprive habeus corpus, conflating common law powers and prerogative. Forced loans were also justified outside the common law. Ship money was not a question of absolutism versus constitutionalism but dishonest use of prerogative in the common law context.

The Petition of Right shows the common law under threat early in Charles I’s reign. His spokesmen were not advocating political ideology but using prerogative where it was unwelcome, thereby questioning the adequacy of its application to the king himself. Hence the Commons rejected the Lords’ attempt to introduce ‘sovereign power’, Coke observing it would place prerogative above the common law because the term was undefined and could not be defined according to the law: the Petition was about the liberties of the English subject, not the monarch’s reserved power. When ship money came to the courts, the judge rightly observed there were no bounds against an ‘unruly king’; but it was broken idiom which had raised the public’s fears. This was a crisis for the common law, and when the Civil War came, it was because Parliament has been taught by Charles the common law was not reliable. Charles I had been exploiting ambiguities which were better left so. The problem of the un-idiomatic speaker is not that he can’t be understood but that he loses control of the mood and nuance.

Ironically, royalists and Parliamentarians didn’t divide according to common law view; they had to choose because religious views (high church versus Protestant conscience) created another fissure. The law had turned to questions of religious liberty, and the un-idiomatic king had played his hand so badly as to lose control. ‘Legal’ no longer meant guided by custom but justified by prerogative in the interest of public welfare.

Burgess draws heavily on JGA Poock’s contention that contemporary thought is explanatory in its own right, versus a tool for understanding. Ironically, he criticizes Pocock for overstating the role of Coke, who had tried to graft Fortescue’s unchanging simplicity onto the common law, contending John Selden was closer to the majority view. In making Coke primes inter pares, Pocock underestimated the common lawyers’ acceptance of evolutionary change, and mistook the role of artificial reason (via custom).