The more that mobile devices, social networks, and data exhaust connect us, the harder it becomes for our actions offline to escape notice, particularly as people comb through public sources. Increasingly, the actions of millions of people online reverberate offline as well, with both inspirational and devastating outcomes.

Last week, a notable example of a positive outcome came out of Philadelphia, where an anonymous “Twitter detective” used Facebook’s social graph search to help real-life police detective Joe Murray (@PPDJoeMurray) to identify a group suspects behind a violent hate crime. The episode combines a number of subjects I’ve explored in this column over the past year, from the use of social media by law enforcement to an emerging “sousveillance state” to the surveillance state to the impact of 24/7 connectivity on relationships to the ethical questions disruptive technologies pose for society.

Just consider: police posted surveillance video on YouTube, asked the public to help identify suspects, and the public responded online, ultimately leading to said suspects “lawyering up.” The fact that someone was able to connect the people on the video to a local restaurant using a public Facebook search is frankly staggering: it’s a reminder that we’re leaving data exhaust behind us as we move through the material world in ways we’re only beginning to appreciate. (If you missed “Actual Facebook Graph Searches” last year, browse through to think through more potential implications.)

I suspect that this episode will become a case study for the use of social media by police departments, and I hope that the Philadelphia police department and prosecutors proceed with care to ensure that no false arrests are made, bringing whomever committed the assaults to justice.

When I first saw this news (on Twitter, appropriately enough) I was reading law professor Danielle Citron’s excellent new book, “Hate Crimes in Cyberspace,” which dives into the negative consequences of connectivity and suggests legal and ethical remedies that may help people who are the targets of abuse and harassment. (Disclosure: Citron is a colleague of my wife at the University of Maryland Law School; I chose to read it and received a review copy of the book from the publisher, given my professional interest in the subject.)

After reading it, I think the book deserves to get a wide audience, particularly as legislatures and tech companies struggle to grapple with the consequences of connectivity. While she writes from the informed perspective of a legal scholar and researcher, the prose is clear and her approach should be accessible to lay audiences.

After a useful, lucid introduction of the issues and tensions, Citron leads the book with a chapter that provides substantive examples of people whose lives have been significantly impacted by online abuse, from a blogger whose life was threatened to a victim of “revenge porn,” and the generally tepid response that such episodes have received from law enforcement, media, and society at large. Online abuse largely goes unreported and, according to research cited by Citron, a majority of targets said they receive no assistance from police in England, Brazil, and India.

People who have not been the targets of hate crimes online may not understand how far-reaching the effects may be. While former US Senator Rick Santorum’s experience with an obscene “Google Bomb” may have provided fodder for late night comics, the experience of being associated with nude pictures, obscene comments, and false accusations is anything but funny for anyone trying to gain employment or enroll in higher education. Search results stay with people, particularly if a group of people make a concerted effort to propagate images of people. Reputational harms are not theoretical in a world where the first action of many human resource professionals, admissions counselors, or prospective dates is to type someone’s name into and Facebook.

As Citron notes, online abuse also can and has led to the worst nightmares of stalking and rape offline. Some young people, faced with revenge porn or abuse, have committed suicide. According to figures from a study in Justice Quarterly cited by Citron, the average financial impact of “cyber stalking” is now $1,200, given the legal fees, child care costs, and moving expenses — and it appears to be endemic, with thousands of such incidents occurring annually in the US alone.

As Citron points out, it took decades before sexual harassment and domestic abuse were viewed as serious issues in the public sphere. For instance, the current furor over the actions of Ray Rice and other National Football League players is taking place in a very different environment than years past. She also documents how various members of the media and analysts have taken a determinist stance towards online behavior over the years. If people log on and express themselves publicly, much less do so about controversial or politically charged issues, the thinking goes, they should expect abuse or invective. That’s “just the way it is.”

I’ve personally seen how female journalists who are simply managing pages or sharing headlines are treated on social media, and I’ve observed misogyny in the tech industry. As Soraya Chemaly notes in her review of Citron’s book, “In the past few weeks, there have been threats to media critic Anita Sarkeesian, violent rape GIFs proliferating on Jezebel, and trolls driving Zelda Williams off Twitter. That online abuse has tangible, real-world effects on the people experiencing them, ranging from stress and psychological trauma to reputational harm, is becoming clearer every day.”

People who take nude “selfies” of themselves or share intimate pictures or videos with loved ones that are then shared without permission online are blamed, as opposed to the people who betrayed their confidence or forced them to participate. In the wake of hacks of celebrity devices and thieves publishing nude photos online, many more people understand such risks, if not always how to mitigate them.

The crux of Citron’s argument is that it doesn’t have to be this way. Citron connects the experiences of women and minorities in the 20th century and the civil rights laws that were enacted to prevent or penalize discrimination against people on the basis of race or gender, with the challenges that confront people in the 21st century. Citron has advocated for the US Congress to criminalize revenge porn, following the lead of states that have passed such statutes.

Tech companies can also take steps to address abuse, given the immense power they hold in the marketplace for ideas and information sharing and retrieval. For instance, Twitter introduced an abuse reporting button last year and vowed to improve its policies this summer. Facebook has been wrestling with free speech, civility, and censorship for years, adding tools to report abuse or violations over time. Google changed its algorithm in 2013 to push down public data shown on mugshot sharing sites in search results and is now taking steps to comply with a European Court’s decision to allow people to “be forgotten.” While this “right to be forgotten” is controversial and raises legitimate concerns about censorship and press freedoms, it also demonstrates that it is possible for the search engine giant to alter what people see if officers of the law require it.

On that count, Citron suggests other potential legal changes, from establishing procedural safeguards in hiring or admissions that give applicants the opportunity to explain results, similar to fair credit reporting practices, to targeting online service providers that earn revenue from hosting non-consensual pornograpy or its removal. Citron also proposes creating the means for pseudonymous litigation, enabling people to pursue legal redress without having to further publicize and associate their real identities with the abuse in question. Whether such legal innovation can successfully be taken up by state legislatures or Congress remains to be seen, particularly in a manner that is nuanced and preserves the balance between freedom of expression and the ability of the press to publish and maintain access to images or data or genuine public interest.

As Citron explores, freedom of speech already has limits online, noting that some expressions that are integral to crime can be subject to criminal penalties. Some invasions of privacy or cruel behavior do not enjoy constitutional protections offline: should their expression online be any different? As I’ve suggested elsewhere, applying the Bill of Rights online is a good starting place for “internet freedom” and civil liberties. Perhaps it’s now time to make the civil rights and anti-discrimination laws that people fought for in the 20th century apply online in this new millennium.