Dozens of federal employees at an obscure agency that handles appeals of patent applications went years with so little work to do that they collected salaries — and even bonuses — while they surfed the Internet, did laundry, exercised and watched television, an investigation has found.

The employees, paralegals making from $60,000 to $80,000 a year, were idle with full knowledge of their immediate bosses and multiple layers of managers and judges who “sat on their hands” waiting for work to give them, a year-long probe by the Commerce Department inspector general’s office uncovered.

Over four years, the underworked paralegals took home more than $4.3 million in pay and about $700,000 in annual performance bonuses of up to $3,500 apiece for “outstanding” work from 2009 to 2013, the report released Tuesday by Inspector General Todd Zinser found.

The underworked paralegals did little as a backlog of appeals of patent examinations doubled from about 12,500 in fiscal 2009 to 25,300 in 2013. Soon after they were hired as legal support staff, the Patent and Trademark Office imposed a hiring freeze that halted hires of judges needed to handle the appeals.

It was easy for the paralegals to goof off with so little work — they worked from home. The patent office set an early example for other federal agencies years ago when it encouraged employees to telework, and the program has been a largely successful model. But the inspector general found that for paralegals in the appeals office, working from home was a green light to abuse the privilege by doing laundry, washing dishes, reading books and a host of other personal activities.

The bonuses included $120,000 for the paralegals’ supervisors, some of whom didn’t check in with their staffs to make sure they had enough work to do.

Employees were told by supervisors to record their hours on timecards under a code known as “Other Time,” the report said.

As soon as they became aware of the investigation, top managers devised other tasks for the paralegals, including assigning them to a project writing an article on the history of the appeals board. But the article was never published, the report found. And most of the other assignments amounted to “busy work” the report called “feeble, half-hearted and ineffective.”

“I almost don’t blame [the paralegal specialists] for watching TV,” one of the chief judges at the appeal board told investigators, “because, I mean, you’re sitting around for 800 hours.”

Zinser described the operation as “a complete breakdown of management.”

“It’s one thing to have idle workers,” Zinser said in an interview, “but in addition to being idle, they received outstanding performance ratings.” He said the Patent Office “displayed a lack of sensitivity” to fee payers who fund the Alexandria-based agency’s $3 billion annual budget.

Patent Office spokesman Todd Elmer said in a statement that the agency is reviewing the report. But he said it already has made “structural improvements” to make the paralegal program more efficient. A new management team is “eliminating underutilization” and revising the way paralegals’ performance is evaluated, Elmer said.

“With new and ongoing improvements, combined with this additional input from the [inspector general], the agency is confident that the [appeals board] will be even more strongly situated to achieve tremendous results for its stakeholders.”

The Patent Trial and Appeal Board reviews appeals of decisions made by patent examiners and decides whether challenges to existing patents are legitimate.

The role of the paralegals is to docket cases, create electronic files, make sure an appeal complies with relevant statutes, and edit judges’ decisions for grammar and style. On occasion, they do legal research for judges. But they rely on judges to give them work.

It is unclear whether there will be changes to telework, a program Zinser said needs more supervision and accountability.

“No need to notify me when work is done,” one supervisor told a paralegal in an e-mail Dec. 18, 2012, in response to a message from the paralegal that she had completed her assigned work at 9:25 a.m. that day.

“It used to get on the supervisors’ nerves, because they knew we didn’t have anything,” the employee told investigators.

Some managers were so fearful of angering the union that represents Patent and Trademark Office employees that they didn’t consider changing the paralegals’ work assignments or even starting the process of layoffs.

But Zinser said the appeals board had options it should have explored with the unions to give the paralegals new duties. Some managers did not know, for example, whether changing work schedules and assignments even needed to be negotiated.