Yoree Koh writes in the Wall Street Journal:

Twitter Inc. has ignited a debate over freedom of speech on the Internet by stripping the verification status of a controversial journalist for violating the social media site’s rules of conduct.

On Friday, Twitter removed the blue check mark on the account of Milo Yiannopoulos, who writes for Breitbart News, a conservative media outlet. He posted a letter on his account that he received from the company, saying that he lost his verified badge “due to recent violations of the Twitter Rules.” Mr. Yiannopoulos denied he has done anything wrong and slammed Twitter for its opaque decision.

“They don’t like me and want to give me a slap on the wrist,” Mr. Yiannopoulos said in an email on Monday. Twitter does not comment on specific accounts.

Twitter did not tell Mr. Yiannopoulos what specific behavior crossed its line. But he has a knack for provocation, having been a loud participant in some of the most controversial firestorms on the social platform, such as the #Gamergate battle over how women are represented in videogames. He has said unkind things about women, taking particular aim at feminists. He has been suspended by Twitter multiple times in the past.

Mr. Yiannopoulos’s demotion comes at a time when Twitter is trying to counter the rampant harassment on its platform. Groups representing women and minorities have criticized Twitter for having an abuse policy that is vague, slow and inconsistently applied.

According to a person close to the company, Twitter executives have in recent months been urging the trust and safety team to take a harder line on abusive behavior than in the past, as stories of online abuse have gained attention. The executives have been pressing for the company to tighten its rules and enforce them more aggressively, this person said.

In a significant step, Twitter recently updated its rules to specify what kind of abusive behavior will not be tolerated, detailing offenses like “inciting others to harass another user” and “if the reported user is sending harassing messages to a user from multiple accounts.”

Twitter does not tell users who submit reports why their report might have been denied. Punishment can lead to temporary account suspension, permanent banishment or taking away their verification status.

Trying to rein in abusive behavior is a tricky issue for Twitter, which has always prided itself as a champion of free speech but doesn’t want that to mean that abusive behavior gets a pass. In the case of Mr. Yiannopoulos, for example, Twitter had multiple avenues. It could be argued that Twitter’s action on Friday was a half measure. It could have suspended his account again or permanently banned him from the site. Instead, it weakened his microphone, an action that some have cried is censorship.