Constitutionalism is committed to the rule of law. In constitutional, rule of law regimes, preexisting rules provide necessary foundations for all government actions. A police officer can arrest persons for burglary only if the legislature has made burglary a crime. As important, in constitutional rule of law regimes, preexisting rules provide the necessary foundations for the ways all government offices are staffed, procedures government officials must follow when making laws, and the laws government officials are permitted to make. A police officer can arrest persons for burglary only if all members of the legislature that passed the anti-burglary law gained office according to law, the anti-burglary law was enacted according to law, the law permits the legislature to pass anti-burglary laws, the police officer was appointed according to law, and the police officer was authorized by law to arrest persons for burglary in the relevant jurisdiction.
The alternatives to constitutional rule of law regimes are rule by status and rule by law regimes. Governance in rule by status regimes is done by the whim of some authority figure who gains power through might or traditional practice. People in a rule by status regime, for example, may always have deferred to the village elders or bow down to the strongest person in the community. Persons are rewarded or punished as pleases those in power. The Queen of Hearts may declare “Off with their Heads,” even when no preexisting law declares the offending action a crime, mandates the death penalty or authorizes the Queen of Hearts to exercise authority. Governance in rule by law regimes is according to preexisting rules by authority figures whose power to make rules is not established by preexisting rules. The dictator governs with the support of the army, but only punishes people who defy his decrees. Political dissenters are shot only when they take actions, including the act of political dissent, that the dictator has previously declared to be punishable by death. Rule by law regimes differ from rule of law regimes because no law justifies the dictator’s power to make official rules. Citizens of the United States may veto laws only when they are elected president by the rules laid down in Article II of the U.S. Constitution. Dictators in rule by law states may make political dissent a crime because they have more guns than anyone else.
Constitutions are higher laws. When ordinary laws conflict, legal authorities follow the most recent enactment. “Last in time is first in line” an old adage declares. The legislature in January declares that the speed limit on the interstate is 65 miles an hour and in February declares that the speed limit is 60 miles an hour, the February enactment governs. Constitutionalism changes this calculus. Constitutional rules are higher than ordinary laws. If a constitutional provision ratified in January declares that the speed limit on the interstate can never be lower than 65 miles an hour, but the legislature in February declares the speed limit to be 60 miles an hour, the constitutional provision enacted in January trumps the ordinary law passed in February. That February law is unconstitutional. By comparison, if a constitutional provision ratified in February declares that the speed limit on the interstate can never be lower than 60 miles an hour, that more recent amendment takes precedent over the previous constitutional declaration that the speed limit can never be lower than 65 miles an hour because both enactments occupy the same place in the hierarchy of laws.
Whether constitutions must be written and subject to judicial review is controversial. Most nations follow the United States. They have written constitutions that are enforced by independent judiciaries. If Congress passes a law inconsistent with constitutional free speech rights, the Supreme Court may declare that law unconstitutional. The United Kingdom does not have a written constitution and courts in that regime have no power to declare laws unconstitutional, hence, Parliament is sovereign. The United Kingdom nevertheless claims to be constitutional regime because Parliament is expected to be guided by a series of unwritten norms that determine who can make laws, how laws are made, and the content of those laws. The Constitution of the United Kingdom is self-enforcing or enforced by voters who have the power to remove at the next election government officials who violate what they believe are their constitutional free speech rights. Both the United Kingdom and the United States are committed to the constitutional proposition, “no taxation without representation.” Americans declared this principle in a written constitution enforceable by the judiciary. The English claim that this principle has existed from time immemorial and is recognized by members of the national legislature.
Constitutional provisions are also expected to be harder to change than ordinary legislation. The Constitution of the United States requires that constitutional amendments be passed by a two-thirds majority of both houses of Congress and then ratified by three-fourths of the states. This is far more demanding that the constitutional rules for passing ordinary legislation. Most states and national constitutions do not require as broad a consensus for amendments. Nevertheless, almost all written constitutions mandate tougher rules for changing the constitution than changing ordinary law. Many states, for example, require a popular referendum to change constitutional rules.
Constitutional government is conventionally understood to be limited government. One limit is inherent in the commitment to the rule of law. If the constitution declares that the president shall be elected every fourth year, presidential elections cannot be held in the third year, even if the president is not doing well or the president decides an election would be good at a time her or she is particularly popular. Liberal constitutions also limit government power. Constitutions forbids certain actions, even when done by officials who gain office according to the constitutional rules and follow constitutional rules for making policy. Legislative powers may be limited. Governmental can only make the laws the constitution empowers the government to make. Congress may not put tariffs on goods shipped from New York to Miami because Article I, Section 9 declares, “No Tax or Duty shall be laid on Articles exported from any State.” The four dissenting justices in National Federation of Independent Businesses v. Sebelius (2012) maintained that no provision in the Constitution authorized the federal government to require individuals to buy health insurance.
Individual rights are the most common constitutional limit on government. The First Amendment forbids Congress from establishing a state religion. The judicial majority in Roe v. Wade (1973), citing the due process clauses of the Fifth and Fourteenth Amendment, forbade the federal and state governments from banning abortion. Rights trump powers. The federal government under the “interstate commerce” clause may ban the interstate sale of plastics, but not the interstate sale of books because the latter is protected by the First Amendment.
Newer national constitutions and many state constitutions emphasize positive rather than negative rights. Negative rights forbid government from taking certain action. The Fifth Amendment forbids government from coercing confessions. Positive rights require government to take certain actions. Constitutions that give persons the rights to certain basic necessities require governments to take the actions necessary to supply persons with food, water, and shelter. Government is limited because government has no choice but to supply those necessities. The Constitution of the United States, which is generally understood to emphasize negative rights, has become a bit of an outlier internationally.
Constitutionalism has many virtues. Constitutions create legal foundations for government action, enable nations to make credible commitments, foster deliberative policies, articulate national ambitions and facilitate the compromises that enable people of different views to share the same civic space. Most important, the rule of law allows persons to organize their lives. The laws may be unjust. The rule of law does not promise a constitution that includes only the good, the true and the beautiful. Nevertheless, persons who are aware of the legal limits on their behavior can better plan their lives and self-consciously decided whether to take certain risks than those who live in a non-constitutional society where rulers can execute people on whims.