May the government suppress, in private workplaces, opinions that it believes are harmful and offensive?
We spend over a third of our waking hours at work. Work is where many people engage in most of their discussions about the issues of the day. Ask yourself what fraction of your talk about political or social matters happens at work--at the water cooler, over lunch, in cartoons on your office door. Giving government the right to censor us in private workplaces would be quite a concession.
Beyond that, every place is someone's workplace. Universities, public buildings, newspaper offices, libraries, restaurants, streets, and parks all contain employees who are in a sense "captive" to offensive speech that goes on there. If the government could restrict speech just to protect "captive" employees, its censorial power would be immense. But the First Amendment, of course, doesn't allow this, even when people can't easily avoid the offensive speech (for instance, when workers must every day pass picket signs that call them "dirty scabs").
(As to the cases Professor Epstein mentions: The court let a city restrict ads on city buses only because they were city property; surely the government can't ban political ads on private buses, no matter how "captive" their passengers are. The abortion clinic casestruck down a ban on signs outside clinics, despite patients' supposed "captivity"; it upheld the ban on loud shouting because the ban was content-neutral, and regulated noise and not offensiveness. I too "invite readers [to read] the cases," and see whether either of us is being improperly "selective" in our descriptions.)
Speech in private workplaces may, of course, be restricted by employers; the First Amendment by its terms applies only to the government. But this is true for all speech on private property. Speech in private universities may be restricted by the university. Private commercial landlords may refuse to rent to the Communists or the Nazis. Speech in churches may be restricted by the church; speech in Slate may be restricted by Michael Kinsley. But none of this empowers the government to suppress what people say in these places.
I propose a dividing line. Harassment law ought not restrict speech (other than threats, slander, and the other unprotected categories) that may reach some willing listeners: Overheard conversations, posters on cubicle walls, newsletter articles, and department-wide e-mail are quintessentially protected by the Constitution, in the workplace or outside it. Unwanted one-to-one speech is different--if the only recipient of the speech doesn't want to hear it, stopping such speech doesn't interfere with communication to other willing listeners. I believe this line fits well with the precedents.
The EEOC and Professor Epstein propose no such dividing line. They claim all speech, including political e-mail and overheard assertions about the inferiority of men, may be punished if it's "severe or pervasive" enough to create a "hostile or offensive" environment (whatever those vague terms may mean). That's just wrong.
Finally, beware proposals to restrict free speech in the name of equality. Equality is important, but so is democracy; so was fighting against communism; so is the nation's power to fight wars; so is protecting police officers' lives against songs urging angry youths to kill cops. These values have likewise been invoked (with the same unsound allegations of "constitutional crash[es]") as reasons to restrict supposedly harmful ideas. The courts now correctly reject these arguments; but if equality becomes a reason to suppress speech, then why not these other values, too?