(Reuters) - A month ago, I told you about a newly proposed $2 billion class action settlement to resolve future claims by people who have been exposed to the Monsanto's Roundup weedkiller and may develop non-Hodgkin lymphoma but have not yet sued or hired lawyers.

I said the new proposal sought to address the serious constitutional concerns raised by U.S. District Judge Vince Chhabria of San Francisco, who is overseeing consolidated Roundup litigation, when Monsanto parent Bayer and class action lawyers made their first pitch for a class settlement of future claims. That first deal – which Bayer and class counsel withdrew before a preliminary hearing, after Chhabria made it clear that he was unlikely to grant approval – would have established a panel of scientists to make a binding, classwide determination of whether and at what exposure level Roundup causes cancer. The new proposal also featured a science panel, but its findings would be advisory, not binding. And the revised settlement would allow future plaintiffs who didn't opt out at the front end of the case to opt out later, after receiving a settlement offer, to pursue their claim in court.

I predicted the new deal was likelier to win preliminary approval from Chhabria because it was more like a conventional mass torts class action settlement, akin to settlements in the fen phen diet drug, NFL concussion and Deepwater Horizon litigation.

I may have been hasty in that assessment. The revised Roundup proposed settlement has provoked its own considerable controversy about the best way to protect the interests of people who don't yet know they are plaintiffs.

Opponents of the proposed futures settlement filed briefs Wednesday and Thursday in the Roundup multidistrict litigation, arguing that the Roundup deal has fatal constitutional flaws: It purports to resolve claims by a class of plaintiffs who don't even have standing to be in federal court because, by the very class definition, they have not yet suffered an injury; and it violates prospective plaintiffs' due process rights by compromising their ability to litigate future claims without assuring that they receive notice of class membership.

This case, according to objectors, isn't like the rare mass torts that have been settled via class actions because the universe of future plaintiffs is both "legion" and "amorphous." Those words, which were quoted in briefs by several objectors, are from U.S. Supreme Court Justice Ruth Bader Ginsburg in her 1997 opinion in Amchem v. Windsor (521 U.S. at 628), which barred a proposed class settlement of claims of pending and future asbestos claims. The Roundup case is like Amchem, objectors said, because it fails to safeguard the rights of perhaps millions of people who may not even yet realize that they were exposed to the weedkiller, let alone that someday they could assert a claim against Bayer.

"It is impossible to provide such 'futures' with adequate notice of their ability to opt out of the settlement class," Public Citizen Litigation Group wrote in an amicus brief opposing the Roundup settlement. "Even if they received notice, it is unlikely that the 'futures' would have the ability to make an informed choice now regarding the valuable rights they will forfeit if they do not opt out."

Bayer and class counsel from Lieff Cabraser Heimann & Bernstein, Audet & Partners, the Dugan Law Firm and FeganScott tried to address that issue by including a back-end opt-out right in the proposed settlement. After the four-year litigation stay, any class member can sue Bayer for compensatory damages, including class members who have sought compensation from the settlement program and are unsatisfied with their offers.

But the objection brief by Goldstein & Russell and Napoli Shkolnik contends that back-end opt out suits will be hobbled by the terms of the class action. Opt-outs can't pursue punitive damages or medical monitoring claims. They can't sue for four years. And they cannot contest the admissibility of findings by the scientific panel. (Plaintiffs or Bayer can contest the findings themselves in opt-out trials, according to the settlement agreement.)

"Despite the contrary assurances of class counsel," the brief said, "the right to litigate that (the proposed settlement) preserves is in truth watered down to the point of being practically water." If Bayer and class counsel were serious about protecting future claimants' due process rights, the objectors argued, the deal would not have called for any restraints on future claims by opt-outs.

The essential problem with the proposed settlement, argued Beck Redden and Stanford professor David Engstrom for objectors represented by Arnold & Itkin and Kline & Specter, is that mass tort class action settlement after Amchem involved classes with "self-conscious and readily identifiable" members. That's just not true, the brief said, in the Roundup litigation, in which "the depth and breadth of the plaintiff-by-plaintiff and state-by-state variations in the proposed class compel the conclusion that common issues do not predominate over individual ones."

Bayer said in an email statement that it remains committed to the proposed settlement. "It is common for class settlements, particularly large ones, to have objectors, but we continue to believe the revised agreement is fair to all parties," the statement said. Bayer denies any link between Roundup and non-Hodgkin lymphoma and continues to sell the product.

Prospective class counsel Elizabeth Cabraser of Lieff Cabraser cast the division between settlement proponents and critics as a dispute about the very purpose of mass tort litigation.

Cabraser said the proposed settlement would allow class members who already have cancer to obtain relatively quick compensation since the settlement allows full payouts to begin as soon as the trial court grants final approval. And those who have been exposed to Roundup but have not developed cancer, Cabraser said, will immediately benefit from the settlement's notice program and diagnostic services. So instead of just having a potential claim for money damages after developing cancer, Cabraser said, future plaintiffs might live longer, healthier lives as a result of the class action — and can still seek those money damages if they get sick.

Cabraser also refuted objectors' constitutional standing and due process arguments. All class members, she said, have standing because they're at heightened risk of becoming ill, just like plaintiffs in class actions resolved with medical monitoring settlements. And the deal, she said, preserves class members' due process right to sue for compensatory damages — the only prospective damages the Supreme Court has cemented as a due process right.

Class counsel's response to objectors is due on March 11.

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