Constitutionalism influences governmental authority by establishing a framework of laws and principles that limit power and protect individual rights. It ensures that authority is derived from a constitution, which promotes a system of checks and balances, enhancing accountability. By defining the relationship between institutions and citizens, constitutionalism prevents the arbitrary use of power, maintaining a rule of law that enhances public trust and stability. Ultimately, constitutionalism not only legitimizes government actions but also empowers citizens to challenge abuses of power, reinforcing democratic governance and respect for fundamental rights.