WASHINGTON (AP) — The Supreme Court ruled unanimously Monday in favor of participants in employee retirement plans who object to companies' investment decisions that eat into retirement savings.

The justices revived claims by current and former employees of energy company Edison International. The employees argued that the company chose mutual funds with excessive fees.

Edison offers employees roughly 40 mutual funds to choose from in deciding how to invest. The case involved a few higher-cost funds open to the general public instead of identical investments with lower costs that are open only to institutional investors. The Edison employees contend that the company did not act in their best interests by choosing the higher-cost funds.

Even a modest jump in fees can have a significant effect on earnings. Higher fees of just 1 percent a year would erase $70,000 from an average worker's account over a four-decade career compared with lower-cost options, according to a study last year by the Center for American Progress, a liberal think tank.

A federal appeals court dismissed the Edison employees' claims under the federal Employee Retirement Income Security Act, known as ERISA. The appeals court said the employees' lawsuit was filed too late to contest the original choice of funds and that executives who make those decisions only have to reconsider them if circumstances change dramatically.

The Supreme Court disagreed with the appellate decision in an opinion by Justice Stephen Breyer. People in charge of investment options have an ongoing responsibility to monitor the situation, Breyer said. "The continuing duty to review investments includes a duty to remove imprudent investments," Breyer said.

The Supreme Court's consideration of the case came amid heightened scrutiny of the management of Americans' retirement investments. The 401(k) accounts, in particular, have increasingly supplanted traditional pension plans. Fifty-three million people held about $4.5 trillion in 401(k) accounts as of Sept. 30, according to the Investment Company Institute, an industry group.

The case is Tibble v. Edison International, 13-550.