Lately, the headlines have been clear: President Donald Trump is headed for a showdown with the courts. If he ignores their rulings, the courts have few tools and limited power to make him comply.

But the real contest is not legal. It is political.

As a political scientist who studies presidential behavior and public responses to unilateral action, I have spent my career examining the boundaries of executive power.

Those limits, aimed at constraining the president, are set in law.

The Constitution outlines the powers of Congress and the president in articles 1 and 2. It formally gives Congress the power of the purse and requires the president to “take Care that the Laws be faithfully executed.”

Statutes dictate how agencies operate, how appointments are made and how funds must be spent. Courts interpret and enforce these rules.

These legal constraints reflect the founders’ concern with unchecked executive power. That concern is embedded in the country’s political origins – the Declaration of Independence was a direct rebuke to royal overreach.

But law alone has never been enough to prevent presidents from abusing their power. The law’s force depends on political will. Presidents often follow the law not simply because they must, but to avoid backlash from Congress, the media or the public.

What the United States is witnessing in 2025 is not just a president testing the system. It is a transformation of the presidency into a fully political institution. The president acts until political resistance becomes strong enough to stop him.

These political constraints are informal and fluid.

They arise from public opinion,........

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