Wang Jian never would have imagined the repercussions he was about to endure the moment he hit a dog with an iron bar.

Within four hours of the incident, the 37-year-old Urumqi man's entire personal life - including his name, phone number, home address and employer - were uploaded online. Within 24 hours, Wang had been inundated by more than 3,000 calls from angry Internet users across the country accusing him of animal cruelty.

What Wang experienced was a virtual version of vigilantism, whereby thousands of Internet users posse-up to expose those suspected of wrongdoing. The Chinese nomenclature for this is "human flesh search," and it can be a double-edged sword.

Earlier this month, a female driver in Chengdu was viciously beaten by another driver after cutting him off. Initial condemnation fell on the man for his "road rage," but after his own dashcam footage was shared, netizens turned their rage toward the woman. A human flesh search revealed that she had 20 previous traffic violations for dangerous driving.

In the old days of vigilantism, a posse (Latin for "power of the community") was often conscripted to pursue outlaws on behalf of authorities. With the advent of technology, citizen enforcement of common law has transitioned online, with netizens becoming the new lynch mobs and social media their execution chambers. A smartphone is a rope and a WeChat account a badge in the human flesh search militia.

Party members are not exempt from China's crowd-powered justice. Last summer in Shanghai, a man riding Metro Line 9 was caught on video touching the exposed thigh of a female university student dressed in short-shorts. After the video went viral, a manhunt to track down the "metro molester's" identity exposed him as Wang Qikang, a senior staff member at a State-owned company, who was eventually disciplined and dismissed from the Party.

Not unlike the cowl of some hooded executioner, the Internet allows concerned netizens to cloak themselves in anonymity while pursuing transgressors. But despite their initial righteous intentions, in every incident there seems to be a point when doxing goes too far.

In the instance of Wang Qikang, his wife's information was also shared on the interwebs, adding to the grief that she was surely already trying to cope with. Even the student whom Wang fondled said she felt even more violated by having been publicly recognized on her campus from the embarrassing video.

Sometimes an appeal on social media for justice can have tragic consequences beyond what the vigilantes intended. In 2013, a Guangdong clothing vendor suspected that a customer had stolen a dress from her shop. She uploaded a screenshot from her surveillance system and made a hue and cry for netizens to assist in the "thief's" apprehension. The alleged criminal turned out to be a senior high school student who, unable to bear the ensuing stigmatism, committed suicide.

Unfortunately, as many human flesh searches are instances of blind hysterics as they are blind justice. Because the deceased high school girl's guilt was never determined, the shop owner was sentenced to a year in prison and had to pay her bereaved family 120,000 yuan ($19,340) in compensation.

And what of Wang Jian, the so-called dog beater? It turns out that he was just protecting his young son from a pack of aggressive street curs. A witness was believed to take offence to Wang's defense, captured the beating on his mobile and uploaded it onto WeChat Moments. A policewoman who saw the pictures supposedly used her resources to uncover Wang's personal information, which she shared on her own Weibo, prompting it to go viral.

There's a fine line between online activism and cyber bullying, and despite the advantages of social media, the next time you post someone's picture online along with a call for a human flesh search, you might first give some thought to how it will affect that person's life, as well as your own.