Prof. Cynthia Estlund (NYU) in the Journal of Free Speech Law on "Can Employees Have Free Speech Rights …

... Without Due Process Rights (in the Private Sector Workplace)?"

Here's an excerpt; read the whole thing here, and see also the broader symposium on Non-Governmental Restrictions on Free Speech:

Both federal and state law include protections, including some in the common law of tort, for speech that advances public policy or the interests of the public. Scores of statutes protect employee whistleblowing, or disclosing illegal or harmful conduct, or claiming other employee rights—for example, reporting discrimination or complaining of violations of the wage and hour laws…. [A]bout half the states protect some kinds of political speech or association by private sector employees (especially that which takes place off-duty and is closely connected to the electoral process). The number and breadth of those laws on their face is surprising; yet they haven't generated a lot of cases, in part because they are not well known and are more or less hemmed in by deference to employer interests and prerogatives.

Crucially, all of these private employee speech protections … take the form of exceptions to the background rule of employment-at-will—that is, the employer's prerogative, absent a contract providing for job security, to terminate employment at any time and for any reason or no reason at all, though not for a reason that is specifically prohibited by law. There are many such prohibited reasons, or wrongful discharge exceptions to employment-at-will, including the speech protections just reviewed as well as the large and still-growing body of employment discrimination law.

But the background rule of employment-at-will undercuts every one of those protections. For employees who suspect or believe that their discharge was in fact wrongful under the law of the land, they first have to identify the wrongful motive (which the employer usually strives to conceal) in order to figure out what claim to file in what forum. Then the burden is on the employee to navigate the obstacle course of adjudication or litigation, and to prove an unlawful motive on the part of the employer, who controls almost all of the relevant documents and employs most of the witnesses….

There are many gaps in the quasi-First Amendment of the private sector workplace; but filling those gaps would do much less to protect employees' freedom of speech than would joining the rest of world in protecting them against arbitrary, unjustified dismissal—that is, by supplying the necessary backstop of due process rights for any employee speech rights. Due process rights in the form of procedural and substantive protection against unjustified dismissal would cast the burden on the employer to show a legitimate and adequate business-related reason for dismissal. Speech that is legally protected (such as union organizing activity or off-duty political speech and associations) would not count as just cause, and the unjust-dismissal review process could provide an accessible forum for airing an employees' claim that the employer's actual reason or motive for dismissal was unlawful. Beyond that, however, requiring the employer to show good cause for dismissal provides a buffer of protection against discrimination or retaliation, and without the doctrinal difficulties of defining the exact boundaries of what is protected, or the often-fatal difficulties of proving employer motive….

The formal free speech rights that about half the states afford in some form … would be far more secure in a just-cause world, yet would still be subject to reasonable employer regulation. And employees in the other half of the states would gain a measure of indirect protection for their political speech and association—especially for their off-duty activity—as an incidental by-product of the employer's burden to prove a good and substantial reason for dismissal….