WASHINGTON — The Supreme Court on Tuesday completes an extraordinary run of oral arguments in cases that could jeopardize the ability of workers and consumers to join forces in lawsuits against companies.

Three times in the past four weeks, the justices have considered petitions from companies seeking to overturn lower court rulings that allowed such lawsuits to proceed. Just by agreeing to hear each case, the conservative-leaning court may have signaled its intentions.

The latest case was brought by Tyson Foods, one of the world’s leading producers of meat and poultry. It wants out of a class-action lawsuit filed on behalf of more than 3,300 current and former workers at a pork processing plant in Iowa who want overtime pay for the time taken to put on and remove protective and sanitary gear.

Tyson’s claim that the workers don’t share enough common traits to sue as a class follows similar cases heard over the past month in which companies argued that consumers could not prove any injury or had been offered complete restitution.

Consumer and labor groups fear the court will follow its past example and rule for the companies in most if not all the cases. In 2011, the court backed Walmart in a class action lawsuit filed on behalf of 1.5 million female employees claiming pay discrimination. In 2013, it denied Comcast’s cable subscribers the right to sue as a class against alleged antitrust activities.

“The stakes for consumer and employment class actions are absolutely enormous,” says Paul Bland, executive director of the legal watchdog group Public Justice. “If the corporate defense side gets what they’re asking for, class actions involving privacy or violations of the wage and hour laws will shrink dramatically, and in many cases become impossible.”

The common issue connecting this term’s cases is what type of injury rises to the level of a lawsuit — in particular, one in which hundreds or thousands of people can join together. The question is important, because while plaintiffs stand to gain from jury awards that can reach into the millions or billions of dollars, companies face potentially ruinous verdicts.

Tyson Foods, for instance, faces $5.8 million in damages under lower court rulings that it refused to pay workers at its Storm Lake, Iowa, processing plant overtime for the minutes they spend preparing for the slaughter or processing assembly lines. That’s a fairly small case; others waiting in the wings involve a $187 million verdict against Walmart and a $1.1 billion verdict against Dow Chemical.

For Walmart, the nation’s largest private employer, it’s a case of déjà vu after winning the larger case four years ago. “As Walmart’s experience illustrates, this is a critical and recurring issue,” it says in a friend-of-the-court brief.

Liberal interest groups fear the business-friendly court — at which the U.S. Chamber of Commerce and other industry associations enjoy winning records — could make it more difficult to prove race or gender discrimination or price-fixing based on statistical analyses.

“Tyson Foods and its allies are urging the court to issue a really broad ruling that would make it harder for injured persons to bring class actions,” says David Gans, civil rights director at the Constitutional Accountability Center. That, he says, could “close the courthouse doors on ordinary Americans.”

In winning lower court victories, attorneys for Tyson employees contended that the company had “plant-wide policies” against overtime pay for putting on and taking off uniforms and walking to and from work stations.

Because the company did not keep time records for those activities, the employees cited studies estimating statistical averages, then computed those estimates into dollars.

Company lawyers argued against such a “trial by formula,” contending the Iowa workers had 420 different jobs and therefore could not have suffered the same injury as a result of the pay policy. Hundreds of them had no claim at all, the company said.

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