The Supreme Court Building is seen on Decmeber 24, 2018 in Washington DC. - The Supreme Court Building is located at 1 First Street, NE and was designed by architect Cass Gilbert (as Gilbert's last major project; he died before it was completed). It rises four stories (92 ft (28 m)) above ground. The construction completed in 1935. (Photo by Eric BARADAT / AFP)        (Photo credit should read ERIC BARADAT/AFP/Getty Images)
Washington CNN  — 

The US Supreme Court on Monday refused to take up a case that would have given businesses the right to contribute money directly to candidates.

The high court, in an unsigned order, declined to consider a challenge to a Massachusetts law barring for-profit corporations from donating to political campaigns. In doing so, the justices kept in place a key pillar of campaign finance law and rejected an opportunity to dramatically expand the court’s blockbuster Citizens United ruling in 2010 that allowed corporations to spend unlimited sums in candidate elections, as along as the spending remained independent of candidates.

That ruling, and a separate appellate court decision later that year, helped give rise to free-spending super PACs.

The Massachusetts’ case was brought by two companies, 1A Auto Inc. and 126 Self Storage Inc., which argued the state’s ban on donations from for-profit corporations to candidates and political committees violated both the companies’ First Amendment free-speech rights and the Constitution’s guarantee of equal protection under the law.

The state, the companies argued, imposes tougher restrictions on for-profit companies than it does on nonprofit corporations and unions. Last year, Massachusetts’ highest court upheld the state’s ban on corporate contributions to political campaigns, saying it serves to prevent corruption.

The owners of the businesses are active in the Massachusetts Fiscal Alliance, a group promoting “fiscal responsibility” and “increased economic opportunity” in the state, according to its website. They were represented in their appeal by the libertarian Goldwater Institute.

All federal candidates are barred from accepting political donations directly from corporations. Twenty-two states also ban corporate contributions to candidates, according to the National Conference of State Legislatures.