Charles Harder, part of President Donald Trump’s legal team, is pushing the Supreme Court to hear a lawsuit that could weaken legal protections for web platforms. Harder’s firm announced yesterday that it had filed a petition in Hassell v. Bird, a defamation case that California’s Supreme Court decided in July. The court ruled that recommendations site Yelp couldn’t be forced to remove a defamatory review from its site, based on Section 230 of the Communications Decency Act — a legal shield that’s been criticized by Republican politicians in recent months.

According to California court records, the Supreme Court petition was filed October 1st. Harder’s press release characterizes it as a chance to “vindicate the rights of all small business owners and all individuals in allowing them to ask a Court to order the removal of defamatory statements that threaten to destroy [their] businesses and personal reputations.” When reached for comment, Yelp directed The Verge to a blog post from July, where it described the suit as “a case that had threatened the rights of online platforms that allow people to freely share their thoughts and the billions of people that do so.”

Hassell v. Bird was filed in 2016 by attorney Dawn Hassell, who accused an angry former client named Ava Bird of making false, negative claims in Yelp reviews. Yelp wasn’t originally named in the suit, and when a court ordered it to take down the reviews, it argued the order violated its legal rights. Lower state courts ruled against that argument, but the California Supreme Court overturned them, declaring that it would “interfere with and undermine the viability of an online platform” if users could take that platform to court for individual users’ posts. (Instead, Bird herself was legally ordered to take down the reviews.)

The case could strike a blow at Section 230

Harder’s firm hasn’t represented plaintiff Dawn Hassell for most of this case. It’s known for taking on high-profile clients like Melania Trump, Jared Kushner, and Hulk Hogan, who retained Harder in his landmark lawsuit against Gawker. But it did co-sign a 2017 supporting brief, which claimed that “if Yelp’s argument were to prevail, the internet would continue to descend into an uncontrolled and uncontrollable wasteland of defamatory content, threats, harassment, and non-consensually posted private sex videos.”

The ACLU, Electronic Frontier Foundation, and many internet companies came out in favor of Yelp. Among other arguments, they contended that increasing the company’s legal liability would either discourage other platforms from letting users freely post comments, or encourage them to avoid any kind of moderation whatsoever, since becoming aware of illegal content could make them liable for it — two scenarios that Section 230 is supposed to help prevent.

Harder’s participation doesn’t tie this case to Trump; as previously mentioned, he’s represented many clients in defamation cases. But Trump, along with other conservative politicians, has argued that web companies are given too much freedom to control what appears on their platforms. A substantial amount of that freedom is provided by Section 230 — and Hassell v. Bird could strike a blow against it.