Voters in roughly half of American states can enact statutes and amend constitutions directly at the ballot box. The mechanism was created deliberately to bypass elected legislatures.
The tool was a Progressive Era remedy
Reformers in the late nineteenth and early twentieth centuries argued that state legislatures had been captured by railroads, mining interests and party machines.
Rather than replace the legislators, they proposed a parallel route: let citizens propose and pass laws themselves when the legislature would not act.
Western states adopted it most enthusiastically, which is why the initiative remains far more common in the West than in the original eastern states.
Adoption spread through state constitutional conventions rather than through any national change, so the rules differ in almost every particular from one state to the next.
Three related devices do different things
An initiative allows citizens to place a proposed law or constitutional amendment on the ballot by gathering signatures.
A referendum lets voters approve or reject something the legislature has already passed, and in some states legislators refer measures to voters themselves.
Recall is separate again, targeting an officeholder rather than a policy. States vary in which of these they permit and on what terms.
Qualification is a signature and verification process
Sponsors must collect signatures from registered voters, usually a share of turnout in a recent statewide race, sometimes distributed across counties or districts.
Signatures are verified by election officials, and campaigns gather well above the threshold to absorb the invalid ones that verification removes.
Because the volumes are large and the windows short, paid signature gathering became a professional industry, which critics say favors well-funded sponsors.
Drafting problems cannot be fixed on the fly
A legislature amends bills through committee and floor process. An initiative is fixed once it qualifies, so any drafting flaw goes to voters intact.
Courts then interpret the text as written, and litigation over ambiguous language commonly follows a measure's passage.
Some states restrict initiatives to a single subject to prevent unrelated provisions being bundled, and disputes over what counts as one subject are frequent.
Amending a passed measure is deliberately hard
Many states limit how a legislature may alter a voter-approved statute, requiring a supermajority or another vote of the people.
Constitutional initiatives are harder still, since changing them requires another constitutional amendment through the same process.
Several legislatures have responded by proposing higher approval thresholds or stricter signature distribution rules, changes that themselves usually must be approved by the voters.
That durability is the point and also the criticism: a measure passed in one political moment can constrain budgets and policy for decades afterward.