In a blow to organized labor, the National Labor Relations Board said employers can restrict the use of company email systems by employees for union-related matters.

The 3-2 decision could have a broad impact, because unions often use company email to update workers about contract negotiations or plans for work stoppages, and also is widely used in organizing campaigns.

The Board ruled that an employer didn’t violate federal labor law by maintaining a policy that prohibited employees from using company email to communicate about union activities. The decision was based on a finding that a company’s email system is a form of property and that employees don’t have a legal right to use company property for personal use.

The decision stems from unfair labor-practice charges filed in 2000 that alleged among other things that the Register-Guard, a Eugene, OR newspaper published by Guard Publishing Co., discriminated against an employee who used company email to tell coworkers about a union rally and other matters.

The decision will enable employers to prohibit the use of company email for union activity, as long as similar communication for other nonwork-related groups like schools and churches are also prohibited said John Raudabaugh, Chair of Labor and Employee Relations Practice of Baker & McKenzie LLP in Chicago.

Mr. Raudabaugh had filed an amicus brief on behalf of the U.S. Chamber of Commerce, arguing that federal labor law doesn’t guarantee employees or unions access to company email. “This case applies to every employer in the United States,” he said.