WASHINGTON — The websites that offer information about President Barack Obama’s health care law survived the government shutdown — even with glitches. But a federal website featuring information about the Amber Alert went dark.

Make any sense? Hardly.

No one really knows who has an essential mission in the federal government and who doesn’t, and that’s why it’s hard to find logical reasons for what’s been open during this partial government shutdown and what hasn’t. The general definition is that anyone involved in protecting life or property works. Everyone else doesn’t.

But there’s no detailed manual, no precise definition of how to figure all this out. The National Institutes of Health will continue to treat current patients but it won’t admit new ones. The NASA administrator is at work but the human resources officer isn’t. The intelligence community sent seemingly nonessential workers home, then called workers back. Walk through the Capitol complex, and you’ll find one restaurant is open while another is closed.

Each agency decides who’s needed. And there’s strong evidence that politics plays a part.

Officially, the calls are made based on guidance issued by the White House Office of Management and Budget, which bases its recommendations, in part, on a Justice Department opinion authored in 1980 by then-President Jimmy Carter’s attorney general. That determination has been interpreted to define essential activities as those that “protect life and property.”

But clearly it’s more acceptable politically to open much more of the Pentagon than, say, the Environmental Protection Agency. And Republicans see barricading popular sites such as the National World War II Memorial in Washington as a Democratic ploy to spark public outrage.

“I think to close down an open memorial like the World War II memorial or the Martin Luther King memorial or any open-air or open-space memorial is a poke in the eye” to Republicans, said Rep. John Mica, R-Fla., the chairman of the House of Representatives Government Operations Subcommittee. “It’s offensive.”

Democratic Rep. James Moran, whose northern Virginia district is home to thousands of federal workers, acknowledged that agency heads are politically attuned, knowing what will be accepted and what won’t.

“Every bit of it is political,” he said. “I think some agencies know that they’re doing work that has been prioritized by one party or another.”

Look at the Pentagon, he said. “I’m not suggesting (Defense Secretary Chuck Hagel) is playing politics in any way. But the fact is that he understands the way it’s going to be viewed by the Congress. I think he feels he can probably get a higher percentage of his employees back,” Moran said. “The Department of Health and Human Services is not so lucky. The IRS is not so lucky.”

If there’s one thing Republicans and Democrats can agree on, it’s that the decision on who’s essential often comes down to a judgment call.

“Any law always has room for some interpretation, and there’s no doubt there’s many shades of gray here,” said John Palguta, the vice president for policy at the nonprofit Partnership for Public Service and a former executive-branch human resources manager.

At the Department of Justice, the federal Amber Alert website went down after employees were furloughed. The system itself wasn’t affected — states and counties issue the missing-child alerts, and at least two were sent over the weekend — but Republicans criticized the move, prompting Justice earlier this week to put the website back up.

Agencies “can’t be totally arbitrary,” Palguta said. “If you wanted to keep the person who is keeping your photocopy machines up and running, someone is likely to say that doesn’t meet the intent.”

He said agencies had flexibility. With Tropical Storm Karen approaching the Gulf of Mexico last week, emergency officials who’d been furloughed were called back in — but now they’re back on furlough.

At NASA, chief Charles Bolden is working because he’s a presidential appointee. But that agency’s chief human resources officer — who helped write the contingency plan — put herself on furlough. “She couldn’t justify her job as being essential to life or property,” Palguta said.

“They’re going to have to explain the decision-making, so they can’t be cavalier about it and find them all exempt,” he said. “If it doesn’t meet the act’s requirements, Congress is going to call them on it, there will be discussions in the media.”

Congress itself is affected: At the Capitol, for instance, anyone considered necessary for security and legislative operations works. Anyone else doesn’t.

Senate doorkeepers, the folks who sit outside the chambers and hold the doors for members to enter, are working. The people who guard the parking lots are not.

There’s not even useful history to guide anyone. After the first of the 1995-96 shutdowns, the House subcommittee on civil service convened hearings to determine what was “essential,” but it didn’t reach a conclusion.

Mica, who chaired the hearing, noted at the time that “the execution of the shutdown was, in many instances, disorganized and illogical, at best, and oftentimes (a) chaotic experience.” His Democratic colleague, Moran, complained that there’d been an inconsistent application of the guidelines used to determine who works and who doesn’t.

They agreed this week that little has changed: “We never have really defined what’s essential, what’s not,” Mica said. “Shame on us, because we’ve been here before and we didn’t resolve this.”

National parks — The governors of at least four states expressed initial interest in an offer Thursday from Interior Secretary Sally Jewell to allow them to reopen national parks in their states, although it remained unclear whether any such deals could be reached soon.

After more than a week of requests from several states that they be allowed to reopen parks closed by the federal government shutdown, Jewell said the administration would be willing to consider such agreements as long as the states agreed to pay the full operating costs, including the salaries of all federal park employees.

“South Dakota, Utah, Colorado and Arizona have all expressed some initial interest in exploring a potential agreement,” said Blake Androff, chief spokesman for the Interior Department in Washington. “But discussions are in the early stages. No formal offers have been submitted.”

— New York Times News Service