IN VLADIMIR PUTIN’S Russia, the bonds between wealth and power are as strong as ever, dominated by friends and cronies of the president who oversee major companies and government ministries. Corruption has been a scourge in Russia since the days of the czars, and it remains pervasive today. On Transparency International’s corruption perceptions index, Russia ranks 143 out of 182, on a par with Nigeria and Uganda, among others.

This is why Alexey Navalny matters. The 36-year-old blogger and lawyer began five years ago to root out corruption at high levels. He probed mysterious financial deals in which hundreds of millions of dollars disappeared from state-owned companies, and he publicized the results. Later, he established a Web site where the public could post examples of corruption. He coined the phrase “a party of crooks and thieves” to describe Mr. Putin’s ruling party, United Russia. And he took center stage as a leader of the opposition when protests broke out in Moscow over rigged elections for parliament.

It is easy to see why the charismatic Mr. Navalny, an unapologetic nationalist, poses a political threat to the powers that be. His anti-corruption campaign was able to build some trust in a nation where it is a rare commodity. He has refused to be silent in the face of pressure from the authorities.

This week, the system struck back. Mr. Navalny was accused of embezzlement, a crime that carries a sentence of up to 10 years, based on an old investigation that was closed without charges three years ago in a Russian region. Mr. Navalny denies the charges. It appears to be trumped-up retaliation for his anti-corruption activity and his role in the opposition.

The latest attempt to quash dissent in Russia is a reminder that Congress needs to approve the Magnitsky Act as part of necessary trade liberalization with Russia. The bill is named after another anti-corruption lawyer, Sergei Magnitsky, who uncovered a $230 million embezzlement scheme by Russian tax and interior ministry officials, then was imprisoned by those officials and subjected to mistreatment that led to his death. The legislation would sanction Russian officials responsible for human rights violations.

The Obama administration has been unenthusiastic about the bill, which awaits floor action. We hope Congress will soon approve the Magnitsky Act along with the trade bill, which would primarily benefit U.S. firms by giving them a level playing field with competitors when Russia joins the World Trade Organization this month. The United States cannot by itself change Russia, but this legislation would show that corruption and authoritarianism have consequences beyond Russia’s borders.

As for Mr. Navalny, a leader more concerned with his nation’s welfare than his cronies’ wealth should award him a medal, not a prison sentence.