The Trans-Pacific Partnership, which has taken a drubbing from all directions during the presidential campaign, will not get a vote before the election.

But as Congress returns to Capitol Hill from a seven-week break, the battle over the TPP continues.

The fight has been given renewed urgency by revelations about the nature of a secret court system embedded in trade agreements. The court system, known as investor-state dispute settlement, or ISDS, has recently been hijacked by hedge funds and other investors, who have discovered that challenging governments over obscure regulatory reforms can be a path to extraordinary profits ― leaving those governments crippled in its wake.

A recent Huffington Post investigation highlighted the financier co-optation of the process, and a four-part series at BuzzFeed on ISDS found deep flaws with the system. The dual reports have hardened critics’ opposition to the 12-nation Pacific trade agreement, which includes an investment chapter with ISDS.

Under this system, a corporation invested in a foreign country can appeal to arbitration panels, consisting of three corporate lawyers, if that country enacts a law or regulation that violates a trade agreement or discriminates against the company. The ISDS courts can then award billions of dollars to the corporation to compensate it for the loss of expected future profits.

The problem is that these courts can also be used by speculators, who buy up companies for the sole purpose of filing an ISDS claim, or who finance lawsuits from corporations for a piece of the claim award.

“ISDS allows a small group of ultra-rich investors to extract billions of dollars from taxpayers while they undermine financial, environmental and public health rules across the world,” Sen. Elizabeth Warren (D-Mass.), an early opponent of ISDS, told HuffPost. “Our trade deals should not include ISDS in any form.”

On Wednesday, Warren hosted a conference call with a group of academics who have traditionally embraced free trade, but who are alarmed by the inclusion of ISDS in the TPP. The group, 223 strong and led by Harvard Law Professor Laurence Tribe, warned that the U.S. will become subject to a flurry of suits by profit-seeking actors with no interest in working through a democratic or constitutional process. During the call, Warren cited the recent HuffPost and BuzzFeed investigations in making her case against ISDS.

The Obama administration, which sees the TPP as a cornerstone of its pivot-to-Asia foreign policy, is still pushing forward. This weekend at the G-20 summit in China, Obama reassured TPP partners. “The U.S. has never had a smooth, uncontroversial path to ratifying trade deals, but they eventually get done,” he said in a press conference.

But that path has become rougher with the reporting on ISDS. The president likely needs a handful of Democrats to pass the TPP, so opposition from the political left could complicate his efforts.

“These new details add urgency to the existing concerns about ISDS and the importance that Congress reject the flawed Trans-Pacific Partnership,” said Sen. Jeff Merkley (D-Ore.). “The ramifications of these ISDS provisions, including erosion of U.S. sovereignty and potential costs passed on to the American public, are extremely troubling ― and they become even more so when hedge fund investors are actively working to exploit this system and pocket profits at the expense of taxpayers around the world.”

Sen. Bernie Sanders (I-Vt.) has also reacted to the news on ISDS, tweeting last week that “this is how corporations have rigged the rules to reward the top 1%, while harming workers & the environment.”

The U.S. Trade Representative’s office did not respond to a request for comment. But a fact sheet at their website maintains that they have improved the ISDS system in the TPP, with “clearer language and stronger safeguards.” They argue that TPP protects the right of member countries to regulate in the public interest, that it establishes guidelines to ensure the independence and impartiality of arbitrators, and that it increases transparency.

Not so, Tribe and his fellow academics warned Wednesday in a letter to Congress:

We write now to express our extreme disappointment that the final text of the TPP that was finally made public in November 2015 did not heed those warnings about this controversial provision’s negative consequences for our legal system. Those concerns expressed in the 2015 letter were based on past agreements and leaked texts from the TPP negotiations. Unfortunately the final TPP text simply replicates nearly word for word many of the problematic provisions from past agreements, and indeed would vastly expand the U.S. government’s potential liability under the ISDS system.

Indeed, Article 9.24 of the TPP, the transparency section of the investment chapter, makes clear that companies or countries need not release anything they deem “protected information,” subject to agreement from the tribunal. And there are no rules around the disclosure of third-party funding in ISDS cases or the arbitrators’ conflicts of interest.

“TPP is an unfair trade deal that will expand a secret court system and make a rigged game worse for workers,” Sen. Tammy Baldwin (D-Wis.) told HuffPost. “When people are struggling to get ahead, the last thing we need is a super court with the power to protect corporations and stick it to taxpayers.”

The other common refrain from the U.S. Trade Representative’s office is that America has never lost an ISDS case. But Rep. Keith Ellison (D-Minn.), one of the leading opponents of TPP in the House, highlighted TransCanada’s $15 billion claim against the U.S. for rejecting the Keystone XL pipeline, which would have transported tar sands oil from Canada to global shipping ports along the Gulf Coast.

“TPP would significantly expand this secret, undemocratic, pro-corporation court,” Ellison said. “It’s great for corporations and wealthy investors, and terrible for just about everyone else. That’s why so many Americans oppose the TPP, and that’s why progressives like me are fighting in Congress.”

Jeffrey Sachs, a professor at Columbia University who signed Wednesday’s letter, warned that Obama’s efforts on behalf of TPP could be politically disastrous for Democrats, potentially hurting former Secretary of State Hillary Clinton in her bid for the White House.

“It’s absolutely a disgrace for President Obama to be pushing this at the last moment,” Sachs said during the call with Warren. “He’s playing with fire right now, and not just after the election, but with the election.”

The use of ISDS as a moneymaking engine, rather than for its initial purpose ― to protect foreign investors from having their factories expropriated or their businesses nationalized ― raises the question of whether there’s a better system available.

“Why should hard-won sovereign advances, like rules against polluting or consumer protections, be at risk when the obvious solution is for the investors to put their skin, not ours, in the game?” wondered Jared Bernstein, former chief economist to Vice President Joe Biden and a critic of TPP. “The simple solution is to have them self-insure against investment losses.”

Self-insurance would put private money at risk, rather than taxpayer dollars, in the event of discriminatory conduct against foreign investors. And the corporations themselves would fund the system through premiums.

“According to USTR, we never lose these cases, so premiums should be cheap,” Bernstein said.

But how could a system of dispute settlement be dismantled when it’s already embedded in more than 3,000 active trade agreements?

“I’d say let them figure it out,” Bernstein said. “My peeps over at Goldman Sachs could cook up this product in a New York minute. In the next minute, they’d start selling credit default swaps off of it.”