Immigration illustrates both how Congress can accumulate sweeping power over a policy area and what happens when it fails to use that power coherently.

How Congress gained power 

The Constitution does not give the federal government an explicit power over immigration—states regulated it for much of the United States’ early history. 

Federal authority grew through a series of Supreme Court decisions in the nineteenth century, culminating in an 1889 ruling that held Congress possesses near-total “plenary power” over immigration as an inherent aspect of national sovereignty–a power that is largely free from judicial review. That ruling remains the foundation of immigration law today.

When Congress used that power

Congress has exercised that power actively at various moments—establishing national quota systems in the 1920s, dismantling them in 1965, and repeatedly restructuring enforcement agencies and the U.S. border security system. 

When Congress stopped acting

In recent decades, political gridlock has increased and comprehensive immigration reform has repeatedly collapsed in Congress:

• 2006–2007: Senate bills died in the House
• 2013: Bipartisan Senate bill passed (68–32), but stalled in the House
• DREAM Act: Passed the House twice, failed in the Senate

What happens when Congress stops acting

The consequences of this inaction are far-reaching—and have grown more visible in recent years.

Because Congress has not updated the basic architecture of immigration law since the 1980s and 1990s:

• Visa levels are outdated
• Asylum procedures aren’t adequate
• We use border systems designed for a very different era

As a result, successive presidents have been left to fill the gap through executive action alone. 

The shift to executive power

As legal scholars Adam Cox and Cristina Rodriguez have documented, Congress has gradually ceded immigration policymaking to the White House through a combination of explicit delegation and simple inaction, transforming the president into a “co-principal” in shaping immigration law. 

The result is a pendulum: programs like DACA and Temporary Protected Status, each affecting hundreds of thousands of people, exist entirely through executive action rather than legislation, meaning they can be created by one administration and revoked by the next. In the Trump administration’s second term, that pendulum has swung hard. The administration took more than 500 immigration-related actions in its first year, invoking the Alien Enemies Act, deploying the military to U.S. cities, and terminating temporary legal protections for more than 1.5 million people—all primarily through executive authority rather than new legislation.

Congress’s role has largely been to fund enforcement: in July 2025 it provided $170 billion for immigration enforcement over four years, including $45 billion to expand detention capacity. But it has not enacted the systemic reforms—updated visa levels, a functioning asylum system, a path to legal status for long-term residents—that only legislation can provide. 

The U.S. immigration system remains, in the words of one immigration policy expert, “outdated, overwhelmed, and under-resourced” because Congress has declined to use the power it indisputably holds.