The barons proposed a system of checks and balances against tyranny.

Evidence

After forty years’ experience of the administrative system established by Henry II the men who now confronted John had advanced beyond the magnates of King Stephen’s time. They had learned to think intelligently and constructively. In place of the King’s arbitrary despotism they proposed, not the withering anarchy of feudal separatism, but a system of checks and balances which would accord the monarchy its necessary strength, but would prevent its perversion by a tyrant or a fool. — Winston Churchill, A History of the English-Speaking…, 394

Categorization

• corroborated: 2 independent passages support this claim — Winston Churchill, A History of the English-Speaking…, 394
• XREF: connects to: A republic’s stability rests on assurance that all will respect shared rules. — Adelin-Costin Dumitru, Forging the Resistive Republic: Social…, 18