James Martin/CNET

Twitter is being sued by a Canadian blogger who says she shouldn't have been permanently banned from the social network for her tweets about transgender people.

Meghan Murphy, founder of the blog Feminist Current, says in the lawsuit that the company locked her account last year and asked her to pull down a tweet that said, "Men aren't women." The tweet was part of Murphy's argument that gender is assigned at birth. Murphy also clashed with Twitter over tweets that asked, "How are transwomen not men? What is the difference between a man and a transwoman?"

In November, the argument reached a crescendo when Twitter permanently booted Murphy from the platform for violating the site's rules against hateful conduct, after she referenced a transgender woman as "him."

Twitter's decision came after it updated its policy against hateful conduct last year. The updated policy bars users from referring to a transgender person with the incorrect pronoun, a practice it calls "misgendering." The company also prohibits users from addressing transgender people by birth name, a practice that's known as "deadnaming."

Murphy, who filed the lawsuit on Monday in the Superior Court of California, alleges that Twitter violated its agreement with users when it changed the hateful conduct policy without alerting the public.

"The policy is arbitrary and it conflicts with Twitter's promise to have an open and free platform for communication," said Adam Candeub, one of the lawyers representing Murphy. The lawsuit cites the state's unfair competition law.

The lawsuit accuses Twitter, which champions free expression, of "false and deceptive advertising."

Twitter pushed back on Tuesday, calling the lawsuit "meritless." The company said it "will vigorously defend itself against this suit."

Silicon Valley tech companies, including Twitter, are struggling with allowing free speech while combating harassment, hate speech and other offensive content. They've faced allegations that they're suppressing conservative speech -- charges the companies have denied.

Murphy is being represented by Dhillon Law Group, the same law firm that filed a discrimination suit against Google after the company fired employee James Damore after he wrote a controversial memo about the gender and diversity gap.

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