Legislative hearings are supposed to be fact-finding missions – a bill comes before a committee, proponents and opponents testify, and lawmakers ask questions to understand the implications of the proposed legislation.  But hearings can also serve as the backdrop to rally support for a cause, more of a set-piece for impassioned political theater than an effort to understand complicated legislation.

The latter role was very much the one on display at a hearing Tuesday on a bill that would pressure National Grid to bring back 1,250 locked-out steelworkers. A bill did come before the Telecommunications, Utilities, and Energy Committee and dozens of proponents and one opponent testified. But lawmakers focused their questions on only one side.

The bill, filed by Rep. James O’Day of West Boylston, would require Grid to provide health insurance to its locked-out workers and bar the company from receiving any rate increases or public money until the employees are back on the job.

The hearing was very successful in drawing attention to how the utility lockout was threatening the livelihoods and in some cases the lives of the company’s workers. Brian and Michelle Harvey of Braintree described how they lost their health insurance while they were attempting to care for a young son struggling with cancer. “What National Grid did was wrong and it devastated us,” said Michelle Harvey, struggling to hold back tears. “All I can say is shame on them. Health care should not be a negotiating tool.”

Over the course of three hours, there were many such gripping stories illustrating the draconian nature of a lockout. There was also testimony about how the replacement workers hired by National Grid were doing a bad job, endangering public safety. John Buonopane, the president of one steelworkers local, urged the lawmakers on the committee to send a message to National Grid, which was described throughout the afternoon as a greedy, giant, multinational corporation.

Only one lawmaker posed a question to union members and their supporters. Sen. Michael Barrett, the cochair of the committee, asked Buonopane whether the Legislature should designated the gas workers as essential employees, which would mean they couldn’t be locked out but also couldn’t strike. (Before being locked out, the union had voted to strike.) Buonopane didn’t answer the question directly, but instead pointed out that the union hadn’t gone on strike in 50 years though it had faced two lockouts over the last 25 years.

There were plenty of other questions that could have been asked to shed more light on the situation.

National Grid, for example, says its five-year offer to its steelworker unions includes pay increases that would boost the current average employee salary from $120,000 a year, including overtime, to $137,000. The offer also includes a 10 percent increase in the pension plan for current employees. New employees, however, would be assigned to a 401k plan with a 3 to 9 percent company match. The company’s health insurance proposal would also introduce deductibles and coinsurance for the first time.

Steelworkers at the Tuesday hearing on National Grid legislation.No lawmaker asked whether the company’s numbers were accurate, or why the offer was unacceptable. (Grid had said all of its other unions had accepted similar terms.)

But lawmakers found their voices when Marcy Reed, the Massachusetts president of National Grid, testified against O’Day’s bill. She and a colleague were asked about the company’s morality, its claim that it wasn’t making much money in Massachusetts, and its “insulting” suggestion that workers who had voted to strike could endanger public safety by just walking off in the middle of a job.

Throughout Reed’s testimony, she was heckled by a handful of steelworkers and their supporters in the packed hearing room. As Reed talked, people in the audience provided their own running commentary, some shouted out “not true” to her statements, another yelled “bullshit” to one of her points.

No one was invited to testify who could address the National Grid contention that any legislative intervention in a private labor dispute would be a violation of federal law. That is a huge question looming over efforts by lawmakers on Beacon Hill to step into the fray, but Tuesday’s four-hour hearing provided no answers.

The plight of locked-out workers has overshadowed the company’s financial concerns and drawn widespread political support. House Speaker Robert DeLeo, normally a friend of business, has taken a strong interest in the labor dispute, supporting the O’Day legislation and a separate bill providing additional unemployment benefits to the locked-out workers. Gov. Charlie Baker has been less active in pushing legislation, but he has made clear the lockout needs to end and end soon.

Even with emotions running high on the issue on Beacon Hill, a hearing is an ideal setting to understand all of the ramifications of a piece of legislation. On Tuesday, however, that didn’t happen. It was a missed opportunity.