Section 7 of the National Labor Relations Act protects the rights of employees to discuss wages and other benefits with each other and nonemployees. By maintaining a rule that restricts employee freedom in this regard, an employer violates Section 8(a)(1) of the Act.
How does this play out in the real world? Find out after the jump...
An example comes from a recent case in which an upscale women's clothing store had this in its employee handbook:
Wage and Salary Disclosure
Compensation programs are confidential between the employee and [employer] Disclosure of wages or compensation to any third party or other employee is prohibited and could be grounds for termination.
Yeah, that'll do it all right. Or how about this? (Same employer)
Commercial Information Security
As a matter of course employees of [employer] will have access to confidential and proprietary information. This information includes, but is not limited to, personnel information, pricing client lists, contractual agreement, intellectual property and marketing/sales strategies. It is a condition of employment that you not disclose this information to third parties during or after employment. Disclosure of [employer] confidential information without express written approval is prohibited. (emphasis added).
Not as clear-cut as the first example, but the ambiguous "personnel information" was construed by an Administrative Law Judge in the case linked above to forbid employees from disclosing wages and compensation.
Many businesses place restrictions on the ability of employees to share purportedly confidential or proprietary information. Nothing wrong with that, except be very careful not to overgeneralize what may constitute confidential or proprietary information. Anything that could reasonably be construed as precluding an employee from discussing wages and benefits -- like, for example "personnel information -- is going to rub the National Labor Relations Board the wrong way.