Let’s look at two states that have or are in the process of reforming campaign finance by referendum:

Colorado

The Colorado Campaign Finance Initiative, or Initiative 27, was a constitutional amendment that was approved by the voters in 2002. The measure limited political contributions for candidates, political parties and political committees:

Individuals can contribute no more than $550 to candidates for Governor or candidates for other statewide offices.
They can contribute no more than $200 to candidates for the state Senate or House of Representatives.
Corporations and unions cannot directly contribute to candidates for office, but these groups can make unlimited contributions to ballot measure campaigns.

The language of the initiative was blistering:

Section 1. Purpose and findings

The people of the state of Colorado hereby find and declare that large campaign contributions to political candidates create the potential for corruption and the appearance of corruption; that large campaign contributions made to influence election outcomes allow wealthy individuals, corporations, and special interest groups to exercise a disproportionate level of influence over the political process; that the rising costs of campaigning for political office prevent qualified citizens from running for political office; that because of the use of early voting in Colorado timely notice of independent expenditures is essential for informing the electorate; that in recent years the advent of significant spending on electioneering communications, as defined herein, has frustrated the purpose of existing campaign finance requirements; that independent research has demonstrated that the vast majority of televised electioneering communications goes beyond issue discussion to express electoral advocacy; that political contributions from corporate treasuries are not an indication of popular support for the corporation’s political ideas and can unfairly influence the outcome of Colorado elections; and that the interests of the public are best served by limiting campaign contributions, encouraging voluntary campaign spending limits, providing for full and timely disclosure of campaign contributions, independent expenditures, and funding of electioneering communications, and strong enforcement of campaign finance requirements.

According to Ballotopedia, “While the measure has not been specifically overturned, its provisions limiting corporation and labor union contributions would likely be found unconstitutional after the U.S. Supreme Court ruling in the case of Citizens United v. FEC.”

Given the changes to the composition of the Supreme Court, however, it is now hard to predict the future of cases built on the Citizens United decision.

Missouri

A constitutional amendment to limit campaign contributions appears on the 2016 ballot. This is actually an attempt to reinstate limits that were repealed by the state legislature nearly a decade ago. According to The Kansas City Star:

The measure would cap donations to candidates at $2,600 per election and to political parties at $25,000. It also would impose other campaign finance restrictions aimed at preventing political committees from obscuring the source of their money.

In November 1994, 74 percent of Missouri voters approved a ballot measure limiting contributions to state candidates. The Republican-led General Assembly repealed contribution limits in 2008, which at the time stood at $1,350 for statewide candidates, $675 for Senate candidates and $325 for House candidates.

Since the ’70s, a number of states, including Illinois (1970), Pennsylvania (1971), Montana (1972), Massachusetts (1972), Hawaii (1978) and Rhode Island (1978), have added environmental rights provisions to their state constitutions.

Hawaii’s Constitution includes a number of environmental protection provisions, including Article XI, section 9: “Each person has the right to a clean and healthful environment, as defined by laws relating to environmental quality, including control of pollution and conservation, protection and enhancement of natural resources. Any person may enforce this right against any party, public or private, through appropriate legal proceedings, subject to reasonable limitations and regulation as provided by law.”