Charles Harder, who has represented President Trump and Hulk Hogan in legal disputes, now wants to take Yelp to the U.S. Supreme Court over a pair of negative reviews.

The country's highest court would have to agree to hear the case and rule to overturn a lower court's decision, but the outcome could have widely felt implications on websites that host user-generated content like Facebook, Google and Twitter.

The case calls into question a legal provision called Section 230, which protects publishers of user material from liability related to those posts. Under Section 230, Facebook can't be held responsible for threats a single user makes against another on its platform, for example.

But the case Harder is petitioning to the Supreme Court — centering on a Yelp review that Harder claims to be defamatory — could muddy those publisher protections.

Harder's client, attorney Dawn Hassell, sued a former client for leaving negative and false reviews of her law firm on Yelp. Hassell wanted Yelp to take the reviews down, but the company refused, claiming First Amendment rights and the right to due process, saying it had not been properly named as a defendant in initial court proceedings.

The case was heard before several more courts, and in July, the Supreme Court of California ruled in Yelp's favor and determined the company did not have to remove the reviews.

Harder claims the refusal to remove falsely negative reviews threatens small business owners, and Yelp claims the insistence to remove the posts threatens free speech and public forums.

Yelp declined to comment, and pointed to a July blog post that claims the case "threaten[s] the rights of online platforms that allow people to freely share their thoughts and the billions of people that do so."

Harder is best-known for representing former pro wrestler Hulk Hogan in a defamation lawsuit against Gawker Media. The lawsuit, which was bankrolled by tech magnate and Trump supporter Peter Thiel, resulted in $140 million verdict for Hogan and drove Gawker into bankruptcy; the case was later settled for $31 million. President Trump hired Harder earlier this year to represent him in an arbitration battle with former aide Omarosa Newman.