This isn't about transparency, it's about intimidation.

By TRACIE SHARP and DARCY OLSEN

When voters in Missouri, South Dakota, Washington and Oregon go to the polls in November, they will vote on ballot measures that are cleverly marketed as legislation aimed at reducing “big money” and “outside influence” in local elections. If passed, what these measures would really do is limit the ability of nonprofits like ours to weigh in on policy matters we care about. This is an infringement of our First Amendment rights.

The South Dakota Government Accountability and Anti-Corruption Act is a good example. Also known as Measure 22, it would force nonprofit organizations to report the names and addresses of their donors to the state government, subjecting them to possible investigation by an unelected ethics board that is given the power to subpoena private documents and overrule decisions made by the state attorney general if the board disagrees.

Nonprofit organizations—like the Sierra Club, Planned Parenthood, National Rifle Association, churches, Boys and Girls Clubs and art museums—are legally allowed under federal law to take positions on legislative matters that impact their missions, as long as they do not financially or otherwise support candidates for office. Because they are not engaging in candidate campaigns, they are allowed to protect the privacy of their financial supporters. The South Dakota measure and others like it would overrule these protections.

The South Dakota legislation is part of a growing national trend. Since 2013, 17 states have considered, and five have passed, state laws to require donors to charitable groups and nonprofits working on issues—not campaigns—to report the names and addresses of their donors to the government.

Once collected, this information is posted on a public website for anyone to access. This might not sound like a big deal in today’s era of living our lives online, but some historical context is in order.

In the 1950s the state of Alabama tried to force the NAACP to turn over its membership list, with the result that segregationists could show up on the front lawns of those who supported the civil-rights movement. In NAACP v. Alabama (1958) the Supreme Court recognized the physical dangers this invited, and the threat to the First Amendment, which guarantees our right as Americans to express ourselves not only with words, but with actions and dollars as well.

Things have certainly changed since then, but we know from personal experience that violence directed at people who support controversial issues is still a real threat.

In 2011 the Goldwater Institute was engaged in a high-profile public dispute with local officials and the National Hockey League over the legality of a multimillion-dollar subsidy to Arizona’s hockey team. During that fight, hockey fans used property tax records to find the home address of the institute’s president, Ms. Olsen, and post it online. The next day a gutted rabbit was found on her porch and the animal’s blood smeared over her house.

In 2012 the Arlington, Va., office of Ms. Sharp’s nonprofit organization, the State Policy Network, was broken into and trashed. In 2013 the homes of our colleagues at the Wisconsin Club for Growth were raided in predawn, paramilitary-style assaults by the police who were looking for evidence that the group was illegally coordinating with the campaign opposing the recall of Gov. Scott Walker. But the group had not run one ad in support of Mr. Walker, sent one piece of mail, or made any phone calls; it simply spoke out in support of his union reforms. Staff at the Freedom Foundation in Washington state had their car tires slashed; an attorney at the Mackinac Center in Michigan was spat upon, the CEO of the Illinois Policy Institute’s home was vandalized, and so on.

Non-conservatives are also targeted. Last Thanksgiving a man went on a shooting rampage in a Colorado Springs Planned Parenthood clinic, tragically killing three and wounding nine others. What if the state had forced Planned Parenthood to post a list of its donors online? How much worse and widespread could that tragedy have been?

Do we want America to be a country where government keeps public lists of law-abiding citizens because they dare to support causes they believe in? Every American has the right to support a cause or a group without fear of harassment or intimidation. Protecting donor privacy is essential to safeguarding that right.

Ms. Sharp is president of the State Policy Network. Ms. Olsen is president of the Goldwater Institute.

Top Stories