You might have been following the latest news on Ellen Pao, the interim CEO of Reddit, who just resigned her position last week. Ms. Pao was also the plaintiff in a high profile sexual harassment lawsuit against her former employer, the venture capital firm Kleiner Perkins. That lawsuit ended with a jury verdict for Kleiner, and most recently the judge ordered Ms. Pao to pay $276,000 to Kleiner to reimburse the firm for some of its costs in defending the action.

Ms. Pao’s resignation from Reddit, however, raises different and potentially disturbing implications about the potential for harassment and abuse over social media.

As background, Reddit and Ms. Pao came under criticism over the past several weeks after Reddit terminated the employment of executive Victoria Taylor, a move which turned out to be wildly unpopular among Reddit’ s online community. As a first stage of protest, many of the sites message boards were shut down by the “moderators,” volunteers who monitor the “sub-Reddit,” the smaller user communities within Reddit. Ms. Pao then apologized on July 6 for the handling of Ms. Taylor’s dismissal, and for a “long history of mistakes” by the company. That apparently did not quell the uproar or satisfy her critics. An online petition demanding her dismissal garnered 213,000 signatures. More disturbing, however, were the comments Reddit users began posting about Ms. Pao. I have looked at some of these comments myself, and some are truly horrific. They range from profanity, some of which is blatantly sexist and racist, to death threats. Of course, most of these posts were anonymous.

Putting aside why Ms. Taylor was terminated (which no one other than the Reddit management team knows) or whether Ms. Pao and the Reddit management handled that correctly, Ms. Pao clearly did not deserve the hateful comments which were directed at her. Even Reddit’s Chairman Sam Altman came out, as he was announcing her resignation, to criticize some of the comments about her, calling it “sickening”. Other former Reddit moderators, such as Katherine Cross, have since observed that the Reddit platform seems to incite abuse by “harassment swarms” that are “ginned up by the websites more toxic users and communities.”

This incident offers a high profile example of the kind of anonymous bullying which can occur on social media, and which employers should be wary of among their own employees. The ability of your employees, whether using some message board or social media or internet site, to post nasty or abusive or discriminatory comments about their co-workers or managers is a growing problem. Studies and experience have shown that people are much more willing to “say” mean and abusive things when they can hide behind the anonymity of the internet. There is also a “mob” mentality, when a group of people gather on a site, and start feeding off each other. This Ellen Pao incident is a prime example of such cyber-bullying.

Adding to the complexity of this issue, an employer’s ability to discipline employees for this type of behavior is limited by the National Labor Relations Board, which has taken a very expansive view of employee “protected activity.” Thus, you must proceed carefully before you discipline an employee for social media activity.

The law requires employers to maintain a workplace which is free from abuse and harassment, whether that abuse happens “live” or is received electronically. This is a huge challenge, especially if an employee complains of abuse which they are receiving outside of work hours, through electronic channels which the employer does not control. The law will not expect you to work miracles, but you will be expected to respond to such a situation. When I have faced this with clients, we have made an attempt to investigate internally and then have assisted or supported the employee if she has chosen to the police to make a complaint. Again, while it is impossible for an employer to monitor all of your employees behavior, you do need to take the steps you can to prevent on-line harassment if you become aware of it.