Right-leaning legal activists along with Elon Musk’s artificial intelligence company have brought sweeping challenges against a cornerstone of legal enforcement in the United States: the right of private groups, people and local governments to sue over violations of many major laws.

Their argument, supported by the Trump administration, is that the Constitution reserves tremendous power for the president and federal agencies to decide how — or whether at all — to enforce federal law. They contend Congress should never have handed that power to others through so-called citizen suits that are part of environmental, campaign finance and certain other laws.

Environmentalists say it would be devastating to lose this essential, decades-old tool that is used to impose fines and halt lawbreaking by bad actors. Citizen suits, for example, have extracted millions from heavily polluting oil and gas operations, and ensured that lead pipes in Flint, Michigan, would be removed after its water crisis.

Legal experts say four pending federal cases — one of them filed last week — are moving forward at a time when the conservative majority on the Supreme Court gives opponents of citizen suits a greater chance than ever of success. The hard part for those opponents now is winning early federal cases and creating disagreement between the country’s appeals courts, which may help convince the Supreme Court the issue is important enough for a nationwide ruling.

Back in 2000, a Supreme Court opinion opened the door for that possibility.

“Many of us who worked in this area have been waiting basically 26 years for this shoe to drop,” said Richard Lazarus, a Harvard professor with decades of experience in environmental law.

Lazarus was referring to former moderate Justice Anthony Kennedy’s comments in a Clean Water Act case that citizen suits raised “difficult and fundamental” questions about whether they improperly dilute executive power. The late conservative Justice Antonin Scalia wrote in a dissenting opinion in the same case that citizen suits turn “over to private citizens the function of enforcing the law.” He avoided explicitly saying they were constitutional.

“The court is more like Scalia’s court since he died than it ever was when he was there,” said Lazarus.

He observed that those who lost cases where Scalia dissented are rushing back to today’s court hoping for a more favorable result.

The critical issue for citizen suits is who — the government or private citizens — collects fines and has control. A person filing a citizen suit must tell the government ahead of time. The government can stop the suit if it sufficiently pursues the case itself, but its options are limited and the person suing can stay involved. Citizen suits can force compliance with the law and result in fines, which go to the U.S. Treasury.

Two lawsuits filed by small businesses are challenging Trump’s sweeping tariffs announced Thursday that impose double-digit levies on 60 trading partners.

The tariffs, implemented under Section 301 of the Trade Act of 1974 for what the Trump administration says is countries’ failure to prevent imports produced by forced labor, cover 99% of U.S. imports. Critics say the goal is less to prevent forced-labor imports and more to replace the worldwide tariffs that Trump imposed last year that were struck down by the Supreme Court in February. They came just as temporary 10% worldwide tariffs — that had also been challenged in court — expired.

Educational toy company Learning Resources, which was part of the tariff lawsuit that won in the Supreme Court, filed a new suit along with several other small businesses in the Court of International Trade on Friday over the current round of tariffs.

The second lawsuit was filed by Burlap and Barrel, a New York-based spice company, and Collective Horology, a watch retailer based in Ventura, California. They are represented by Liberty Justice Center, a libertarian advocacy group.

Both lawsuits argue that the government didn’t adequately establish its case against each specific economy or spell how the tariffs will eliminate the specified practice they are being levied for, as required by Section 301.

“Forced labor is morally indefensible, but an important objective does not give the government permission to ignore the law,” said Sara Albrecht, chairman and CEO of the Liberty Justice Center. “The administration allowed one global tariff to expire and immediately replaced it with another under a different statute. Changing the statute doesn’t change the law.”

The White House did not immediately respond to a request for comment.

Experts say it might be tougher to successfully challenge the current round of tariffs than previous rounds. Trump used Section 301 to impose big tariffs on China in his first term, and they survived court challenges.

Unlike the Section 122 levies that expired Friday, “these tariffs will be with us for the long haul,” said lawyer Patrick Childress, a partner at Holland & Knight and a former U.S. trade official.

Even if countries enact the precise policies the U.S. wants, he said, they will still need to prove that they’re enforcing them to Washington’s satisfaction before the tariffs are removed. “This suggests that no short-term path for country-wide relief from the new Section 301 tariffs will be available.”

The U.S. government can continue collecting the 10% worldwide tariff it imposed in February while legal challenges to the levies continue to work their way through the courts, a federal court ruled Thursday.

The Court of Appeals for the Federal Circuit in Washington decision handed a procedural win to the Trump administration, concluding that its case was “likely to succeed on the merits.”

At issue are temporary 10% worldwide tariffs President Donald Trump imposed after the Supreme Court in February struck down even broader double-digit tariffs the president had imposed last year on almost every country on Earth. The new tariffs, invoked under Section 122 of the Trade Act of 1974, are set to expire July 24.

Section 122, which had never been used to justify import taxes before, allows the president to impose worldwide tariffs of up to 15% for 150 days, after which congressional approval is needed to extend them.

Section 122 is aimed at what it calls “fundamental international payments problems.” In dispute is whether that wording covers trade deficits — the gap between what the U.S. sells other countries and what it buys from them — as the Trump administration contends.

A split three-judge panel of the specialized Court of International Trade in New York last month found the 10% global tariffs were illegal after small businesses sued to stop them. The trade court ruled 2-1 that Trump overstepped the tariff power that Congress had delegated to the president under the law. The tariffs are “invalid” and “unauthorized by law,” the majority wrote.

Donald Trump fired the new top federal prosecutor in Seattle on Wednesday less than an hour after the attorney was unanimously appointed by the federal judges in the district, highlighting tensions between the courts and the president over the powerful positions.

Roger Rogoff, a former judge and veteran state and federal prosecutor, was sworn in as US attorney before 8am at the US courthouse in downtown Seattle. In a phone interview, he said he then went to the US attorney's office and asked to meet with Charles Neil Floyd, whose 120-day interim term in the position ended in February.

As he waited in a lobby, Rogoff said, he received an email from the Trump administration informing him he had been removed from the position. He is consulting with other lawyers about suing over his firing, he said.

Presidents normally appoint US attorneys, the top federal prosecutors in each judicial district. The positions require Senate confirmation, except in temporary appointments. When temporary appointments expire before a nominee is confirmed, the judges in a judicial district can name a US attorney.

But under Trump, the justice department has sought to leave unconfirmed prosecutors in their positions indefinitely, often through novel personnel maneuvers.

"District court judges can appoint a temporary US attorney, and [the president] can fire them," the acting US attorney general, Todd Blanche, said in a social media post on Wednesday. He added that the judges who appointed Rogoff "abandoned the time-honored process of consultation with the administration so that the selected US attorney is qualified to serve in the administration".

Trump named Floyd, who previously served as an immigration judge, interim US attorney last October but never forwarded his nomination to the Senate. When Floyd's time as interim US attorney expired, Trump simply shifted his title, a tactic the administration has also tried in other federal judicial districts: he named him first assistant US attorney, while the top post was left empty.

In May, a US appeals court panel expressed skepticism that the maneuver was legal. The federal judges in the city decided to take applications for the position, and they appointed a bipartisan panel to review the applications.

On Wednesday morning the court – comprising 17 active and senior judges appointed by five presidents – issued its unanimous order naming Rogoff the US attorney for western Washington.

Patty Murray, a US senator from Washington, who had opposed Floyd for the US attorney job, blasted Rogoff's quick firing.

"Throughout his career, he has demonstrated an outstanding commitment to public service, and he was appointed legally by the federal judges in the western district of Washington," the senator said in a written statement. "This administration doesn't want to deal with advice and consent – they just want to install cronies to carry out a corrupt political agenda."

In December, Alina Habba resigned as the top federal prosecutor for New Jersey after an appeals court said she had been serving in the post unlawfully.

Lindsey Halligan, who pursued indictments against a pair of Trump's adversaries, left her position as an acting US attorney in Virginia after a judge concluded her appointment was unlawful and that indictments she brought against the New York attorney general, Letitia James, and the former FBI director James Comey must be dismissed.

Lawmakers said Kathryn Ruemmler, the former top lawyer at Goldman Sachs and White House counsel to President Barack Obama, was not being truthful Wednesday about her relationship with Jeffrey Epstein, rejecting her testimony that Epstein had merely "used" her.

Ruemmler in her opening remarks told members of the House Oversight Committee that "it was a mistake to deal with" Epstein, but she insisted she never witnessed criminal activity. She said Epstein "used me and other respectable people to legitimize his standing."

Democrats emerged from questioning Ruemmler saying she was not being forthcoming about her ties to Epstein.

"It is difficult to see how she's being completely truthful in there with the answers she's given the committee," Rep. Robert Garcia of California, the top Democrat on the committee, told reporters.

Jennifer Connelly, a spokeswoman for Ruemmler, said in response that Ruemmler had "testified openly and truthfully for six hours and answered every question the committee asked."

Ruemmler is the latest prominent figure called before the House Oversight Committee as lawmakers investigate the network of powerful people connected with Epstein. The bipartisan inquiry has already included testimony from more than a dozen high-profile witnesses, including Microsoft co-founder Bill Gates and former President Bill Clinton, as lawmakers examine how Epstein's wealth and influence may have helped shield him from scrutiny.

Ruemmler served as White House counsel under Obama from 2011 to 2014 and was briefly considered for attorney general. She served as Goldman Sachs' general counsel for six years before announcing in February that she would step down amid backlash over her correspondence with Epstein. Although she said she would step down on June 30, she remains employed by Goldman Sachs.

Lawmakers have focused on Ruemmler's close relationship with Epstein in the final years of his life, pointing to affectionate communications between the two.

"For her to deny that there was any type of real relationship there, I just don't buy it," Garcia said. "And so, again, the fact she is not under oath is very problematic."

While Ruemmler has tried to downplay their relationship in more recent statements, thousands of documents released by the Justice Department showed that Ruemmler and Epstein had an extensive relationship. The files included personal emails, social plans and gifts that extended beyond formal legal work. Documents showed she had called Epstein "Uncle Jeffrey" in emails and said she adored him.

Ruemmler said in her opening remarks that she first met Epstein in 2014 regarding potentially working with him and Gates "to set up a large donor-advised fund." Soon after, according to Ruemmler, she learned about Epstein's 2008 conviction on sex crimes, when he became a registered sex offender.

She said Epstein expressed remorse about it, and that he did not know the women were underaged. She said she "relied on the resolution reached by federal and state prosecutors and validated by a judge as being a proportionate and final resolution of his criminal conduct."

Comer said Wednesday that Ruemmler is the 18th person to testify as part of their broader investigation.

Billionaire investor Leon Black was subpoenaed last month after lawmakers said he refused to answer some questions about his yearslong relationship with Epstein.

Comer said Wednesday that Black will appear for a formal deposition on Sept. 3 but that he expects to have Black's nondisclosure agreements by "the end of the week."

The committee has also expressed interest in questioning acting Attorney General Todd Blanche, whose nomination to permanently lead the Justice Department is pending before the Senate.