Economic citizenship also has important meaning for abortion rights. All liberal justices support the freedom to choose, but it is worth much less to poor women far from services, as many are in the South and West. Decades ago a divided court ruled that Medicaid and other federal programs can refuse to fund abortion while paying for live births and other reproductive care. This is a breach of the usual principle that government may not penalize people for exercising a constitutional right. (Imagine student loans only for those who agree not to vote.) It is time to reopen this question.

Third is a constitutionalism of just criminal justice. Activists are raising a new generation of questions about policing and the prison system: who gets stopped, the system of money bail that keeps arrestees locked up simply because they cannot raise the cash to get out, the ways prosecutors’ offices set priorities, and the widespread and highly unequal incarceration that results.

An earlier generation of court rulings established the right to a lawyer for criminal defendants and protections against arbitrary and abusive treatment by the police. Today we need justices who will address a new generation of issues. They should rule that it violates due process of law to languish in jail, away from work and family, because you cannot make bail. They should hold that constitutional equality is offended when white and nonwhite people — or poor and wealthy people — have pervasively different experiences of criminal justice.

Progressives are winning important victories on these fronts by electing reformist prosecutors, but constitutional rulings can press change throughout the system, not just in sympathetic cities and states. The core work of the law is organizing and disciplining government’s coercive power, and whether that power reinforces racial and economic inequalities or helps to neutralize them is one of the most basic questions for a legal system.

Fourth is a constitutionalism that respects the rights of noncitizens. Spurred by President Trump’s nativism, a new wave of mobilization and solidarity with migrants has highlighted the extreme legal, economic and sexual vulnerability of millions of undocumented residents and workers.

The courts have long tolerated different treatment of foreigners than of United States citizens and authorized residents. But the family-separation crisis at the border has highlighted the American archipelago of lawlessness that asylum-seekers and unauthorized border-crossers face: little meaningful process, and opaque and seemingly arbitrary decisions with life-or-death consequences. The right to due process of law applies to everyone in the power of the United States government, not just citizens. A progressive jurisprudence would strike down policies like family separation and require a decent, intelligible and transparent process to decide on the rights of noncitizens. It would be more expensive than the present system, but legitimacy is not free.

It may seem like pointless fantasizing to plot progressive rulings when the right is tightening its grip on the courts. But these things change quickly: No one expected Mr. Trump to be appointing justices. And the demographic, generational and ideological changes that are reviving the left may well shape decades of politics.