Danielle Keats Citron, a law professor at the University of Maryland, is the author of "Hate Crimes in Cyberspace."

Trolling — like the kind of exploitative abuse spewed against Zelda Williams on Twitter after her father’s death last week — is often nasty and hurtful. But it is routinely protected expression. Internet users are free to use words and images to get a rise out of others, even at their most vulnerable. In this case, two individuals tweeted photographs of dead bodies to a young woman and wrote that her deceased father would be “ashamed” of her — forcing her to quit the service altogether. These acts are offensive, disturbing and mean-spirited, and yet, they are examples of constitutionally protected speech.

Hateful, offensive and distasteful ideas enjoy constitutional protection, so debate on public issues can be “uninhibited, robust and wide open” under the First Amendment.

Law enforcement has the tools to track down individuals that engage in cyber harassment and cyberstalking.

But there is a point when trolling escalates beyond the offensive and shocking into cyberharassment or cyberstalking — actions that are not protected.

Intermediaries — usually the websites where trolls post comments — can step in to revoke the privilege of anonymity, or even remove abusive speech that violates their community guidelines but when trolling turns into cyberharassment or cyberstalking, the law can and should intervene.

Online perpetrators can be criminally prosecuted for criminal threats, cyberstalking, cyberharassment, sexual invasions of privacy and bias intimidation. They can be sued for defamation and intentional infliction of emotional distress. In a few states, they can also be held to account for bias-motivated stalking that interferes with victims’ important life opportunities, such as employment and education.

Law enforcement should be able to use forensic expertise and warrants to track down individuals who engage in this conduct anonymously.

Of course, the law can only do so much: some abuse is left untouched, perpetrators can be hard to identify if they employ certain technologies and, ultimately, lawsuits require significant resources.

This is an opportune moment to educate teenagers about the suffering caused by online abuse. As parents, let’s put talking about cyberharassment on par with discussions about drunk driving. And if we discover that our kids are caught up in trolling or more extreme cyberbullying, no tool is more powerful in changing teenagers’ behavior than the possibility that they might lose their cellphones, computers or social network accounts. We should not squander this chance to reinforce the importance of respect as a baseline norm for online interaction.



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