SAN FRANCISCO — Social media has overflowed with sexual misconduct allegations during the last few weeks. The 450-word post that Melanie Kohler put on Facebook probably had the shortest life — a few hours. It may also have been the first to get its author sued.

As the torrent of accusations continues, it is unlikely to be the last.

“The lid is off,” said Mark G. Clark, a Michigan lawyer specializing in online defamation cases. “Power to the people. Anyone can have their grievance heard. But at the same time, anyone can be irresponsible and malicious.”

He noted that Facebook and Twitter see themselves as neutral platforms that cannot take a side in disputes. So the aggrieved call lawyers. “We get inquiries daily: ‘I’ve been defamed online. What can you do to help?’” Mr. Clark said.

Ms. Kohler, who runs a scuba diving company in Hawaii with her husband, had both narrow and far-reaching goals when she wrote her Facebook post on Oct. 18.