Yes, strikes by federal workers are illegal. But requiring people to work without pay may also be illegal, legal scholars have pointed out. Either way, protest movements often use illegal tactics. It’s called civil disobedience, and it can succeed when the cause is sympathetic. Federal workers forced to visit pawn shops because of a petulant, wealthy president are pretty sympathetic.

The modern labor movement was launched in part by the illegal sit-down strikes of 1936-37, when workers in Flint, Mich., and other cities occupied factories to keep them from operating. The civil-rights movement frequently used illegal tactics. Last year, teachers in Arizona, Kentucky, Oklahoma and West Virginia risked breaking the law by walking off their jobs — and nonetheless won concessions. “One has not only a legal but a moral responsibility to obey just laws,” wrote a certain reverend whose 90th birthday the country is celebrating on Monday. “Conversely, one has a moral responsibility to disobey unjust laws.”

The celebrations of Martin Luther King Jr. will include a lot of pap about peace and equality. But King didn’t think that peace and equality just happened. He thought people had to struggle for them. He understood that most great societal advances in America’s history — independence from Britain, the abolition of slavery, women’s suffrage, decent pay for workers — depended on mass political movements.

The government shutdown, of course, is a minor issue compared with those advances. But it is also a clear sign that the country lacks the sort of popular movement necessary to make progress against today’s great challenges: a fraying democracy and dysfunctional government; a stagnation of living standards for much of the population; a violently warming planet.

The Trump resistance has been the most hopeful sign of activism in decades. Thousands and thousands of people, mostly women, have been inspired to march, organize, dive into local politics and get out the vote. They have already proven that their activism can make a difference. A lot of Americans owe their health insurance today to this new movement.

But relative to the scale of the country’s problems — and the strength of past political movements — the new movement remains too small and too weak. Figuring out how to build it up is a vastly more important question for progressives than, say, figuring out who the ideal 2020 Democratic nominee will be. Get the movement right, and the politicians will follow.

In the meantime, the shutdown reaches its one-month mark by the end of Monday, the same day the country is supposed to be honoring grass-roots activism.