Justice Neil Gorsuch
CNN  — 

A nearly $2 million sale of property co-owned by Supreme Court Justice Neil Gorsuch to a prominent law firm executive in 2017 is raising new questions about the lax ethics reporting requirements for Supreme Court justices.

Property records from Grand County, Colorado, show that the Walden Group LLC – a limited-liability company in which Gorsuch was a partner – sold a 40-acre property on the Colorado River to Brian Duffy, chief executive officer of the prominent law firm Greenberg Traurig.

Duffy and his wife, Kari Duffy, paid $1.8 million for the property on May 12, 2017 – just one month after Gorsuch was sworn in as an associate justice of the Supreme Court.

The sale was first reported by Politico.

The financial disclosure report filed by Gorsuch for the calendar year 2017 lists a sale by the Walden Group LLC for a profit of between $250,000 and $500,000. However, the section where a buyer could be listed is blank. It’s unclear if that’s a violation of ethics rules.

Brian Duffy is currently based in Denver and previously served as president and chair of the Greenberg Traurig’s 600-member global litigation department.

Lawyers at Greenberg Traurig have appeared in numerous cases that have come before the Supreme Court since Gorsuch joined the bench in April 2017. Duffy told Politico that he had not himself argued any cases that were in front Gorsuch, nor had he and the justice met in a social capacity.

“I’ve never spoken to him,” Duffy said, according to the Politico report. “I’ve never met him.”

The Supreme Court has not responded to a request for comment. CNN also has reached out to Duffy and representatives for Greenberg Traurig.

Notably, another lawyer in the Greenberg Traurig’s Denver office led the legal team representing state of North Dakota in a dispute over the Environmental Protection Agency’s authority in regulating carbon emissions as part of the Clean Air Act.

Gorsuch was part of a six-member majority on the Supreme Court that ruled last June in favor of North Dakota and other Republican-led states to cut back the EPA’s authority to regulate carbon emissions from existing power plants.

The Supreme Court has ethics rules, but it’s largely up to high court to enforce them. The justices have refused to be bound by the official code of conduct that applies to lower-court federal judges and that provides more enforcement mechanisms for policing conflicts involving transactions or business relationships with lawyers or others who come before the court.

The opaqueness in how the sale was recorded on Gorsuch’s financial submissions is the latest example of the justices coming under scrutiny. Democratic lawmakers have said that if the Supreme Court does not adopt more stringent ethics rules, Congress could step in. However, Republicans on the Hill have shown little interest in getting involved.

“This is just another example in a long line of examples of the justices feeling that they are wholly unaccountable to anyone,” said Sarah Lipton-Lubet, president of Take Back the Court Action Fund, a group that advocates for greater transparency at the Supreme Court.

“Instead of treating their jobs like the public servants that they should be, they see themselves as above all of us and the rule of law itself,” Lipton-Lubet added.

A version of one court ethics reform bill that has circulated on the Hill would require a cooling-off period in which a judge or justice couldn’t hear a case involving a party, a lawyer or a firm supervisor from whom the judge or justice had received “income, a gift, or reimbursement” that requires disclosure under the judiciary’s ethics rules.

Democratic lawmakers have been scrutinizing recent revelations that Justice Clarence Thomas went on lavish trips that included private jet and yacht travel that were paid for by a GOP megadonor. The bulk of the hospitality went unreported on Thomas’ annual disclosure forms.

Thomas has said he was advised that he was not required to report the hospitality, but he has yet to publicly address a separate real estate transaction involving the donor, Texas billionaire Harlan Crow, that went undisclosed on his submissions.

Chief Justice John Roberts has been invited by Senate Judiciary Chairman Dick Durbin to testify to Durbin’s committee about ethics, but the justice has not responded to the voluntary request.