WASHINGTON (AP) — President Donald Trump has the biggest megaphone, but it's governors and local officials who will decide when to begin reopening their economies after shuttering them to try to slow the spread of the coronavirus. The Constitution largely gives states the authority to regulate their own affairs.

Trump has set Easter, April 12, as a goal for reopening the U.S. economy, though he also has said he will be guided by his public health experts. Unless Americans continue to dramatically limit social interaction by staying home from work and isolating themselves, the number of infections will overwhelm the health care system, many health experts have warned.

Some questions and answers about the legal authority for shutting and reopening the U.S. economy.

___

Q. Does the president have the authority to override state and local orders?

A. No. Under our constitutional system, states have the power and responsibility for maintaining public order and safety. As we've seen since the outbreak began, decisions about limiting social interactions by ordering people to shelter in place, closing businesses and shutting schools are being made by governors and local officials. Those same officials will make the call about when to ease up, no matter the vehemence of Trump's exhortation to have businesses "opened up and just raring to go by Easter." Trump's comments "are just advisory," said John Malcolm of the Heritage Foundation.

Gov. Larry Hogan, R-Md., has ordered all nonessential businesses and schools to close, and he said Thursday on Twitter that he does not see a quick end to the restrictions. "This battle is going to be much harder, take much longer, and be much worse than almost anyone comprehends. We have never faced anything like this ever before, and I continue to urge the people of our state to stay in place at home and stay safe," Hogan wrote.

___

Q. But the president has set a 15-day period in which all Americans are being urged to drastically scale back their public activities. Doesn't that amount to a national order?

A. No. The guidelines are voluntary, and they underscore the limits on Trump's powers. He can use daily briefings and his Twitter account to try to shape public opinion, and he has not been reluctant to do so. "When Donald Trump selects a narrative and begins to advance it, especially through his Twitter account, it has a remarkable effect on those who trust him. The more the president speaks against more robust forms of social distancing (such as shelter-in-place rules), the more noncompliance we are likely to see on the ground level from citizens sympathetic to the president," Robert Chesney, a University of Texas law professor wrote on the Lawfare blog.

___

Q. Still, Trump has invoked some federal laws to address the virus outbreak, hasn't he?

A. Yes, he has. The Stafford Act allows the expenditure of tens of billions of dollars in emergency assistance. The Defense Production Act allows the president to direct private companies to produce goods or acquire raw materials. Trump has yet to actually order companies to do anything, over the objection of some local officials who have a desperate need for ventilators, masks and other equipment. But Trump can only assert powers that Congress has specifically given him. "There are real limits on the president and the federal government when it comes to domestic affairs," Berkeley law professor John Yoo said on a recent Federalist Society conference call. At the same time, the federal government has the power, under laws aimed at preventing the spread of communicable diseases, to quarantine people when they arrive in the United States and travel between states.

___

Q. Is it clear that state and local governments have authority to impose the severe restrictions we've seen?

A. Lawsuits already are challenging state actions on religious grounds and as seizures of property for which the government must pay compensation. But for more than 100 years, the Supreme Court has upheld states' robust use of their authority, even when it restricts people's freedoms. In 1905, the court rejected a Massachusetts pastor's complaint that he should not be forced to get a smallpox vaccine or pay a fine, Malcolm noted.