Cathy Green has never paid much attention to what goes on in Congress. But when she learned that a federal law would allow her pension to be cut by as much as 30 percent, she became alarmed.

Ms. Green, of Lake Stevens, Wash., had claimed her benefit in 2015 after people in the plan were alerted that it might become insolvent. Earned from 20 years of work as an office manager for an insurance company, her pension was part of the Western States multiemployer plan — a type of defined benefit plan created under collective bargaining agreements and funded by groups of employers.

There are roughly 1,400 of these plans nationwide, covering 10.7 million active and retired workers. But a significant number of them had been headed toward insolvency in recent decades, the result of changes in some industries, inadequate funding and the decline in participants as work forces contracted.

To address the problem, Western States cut participants’ benefits in 2018 by 25 percent, on average, under the terms of the Multiemployer Pension Reform Act of 2014. The law aimed to keep plans alive without taxpayer assistance — but it stirred controversy and criticism.

The cuts reduced Ms. Green’s monthly $1,265 benefit by $380, or about 30 percent. “It might not sound like much, but it was a lot for me,” she said.

Three years ago this month, Congress changed course on these plans. As part of a $1.9 trillion Covid stimulus bill, lawmakers approved an $86 billion package for multiemployer plans facing insolvency to apply for one-time federal grants that would keep them viable until at least 2051. The aid was a response to organized pushback against the cuts from union members. But it drew fire from critics, who opposed using taxpayer dollars to bail out private-sector pensions and said the legislation fell short on needed reforms that would prevent future problems. They also said some of the plans were mismanaged.