Congressman Mark Pocan accomplished something remarkable this week. Amid all the wrangling and disarray in Washington, he proposed to end an injustice and got the House to go along with him.

The Wisconsin Democrat who co-chairs the Congressional Progressive Caucus has been an ardent supporter of House Resolution 1, which The Washington Post describes as “perhaps the most comprehensive political-reform proposal ever considered by our elected representatives.”

Sponsored by Congressman John Sarbanes (D-MD) this “For the People Act” is designed “to expand Americans’ access to the ballot box, reduce the influence of big money in politics, and strengthen ethics rules for public servants and for other purposes.” It does all that. And, thanks to Pocan, it also addresses one of the great injustices in American politics—prison gerrymandering.

“The way the Census Bureau counts people in prison creates significant problems for democracy and for our nation’s future. It leads to a dramatic distortion of representation at local and state levels, and creates an inaccurate picture of community populations for research and planning purposes,” explains the Prison Policy Initiative “The Bureau counts incarcerated people as residents of the towns where they are confined, though they are barred from voting in 48 states and return to their homes after being released. The practice also defies most state constitutions and statutes, which explicitly state that incarceration does not change a residence.”

Because Census data is used for redistricting at every level of government, prison gerrymandering creates distorted maps. In an era of mass incarceration, this distortion creates an even greater injustice because, as the Prison Policy Initiative explains, “counting the people in prison in the wrong place now undermines the Supreme Court’s requirement that political power be apportioned on the basis of population. The process of drawing fair and equal districts fails when the underlying data are flawed.”

According to the National Association for the Advancement of Colored People, “the practice of counting prisoners as residents of the state legislative districts where they are incarcerated rather than in their home districts” is especially damaging to democracy in states where prisoners from urban areas—many of them African Americans and Latinos—are sent to prisons in rural areas. “The effect is that white, rural voters in the districts where prisons are located have their electoral power unconstitutionally inflated, at the expense of voters of color in other, over-crowded districts,” explains the NAACP.

When H.R.1 was being debated by the House on Thursday, Pocan proposed an amendment to “end the practice of prison gerrymandering whereby incarcerated persons are counted in Census population counts as residents of correctional facilities and not their most recent residence prior to imprisonment.” In addition to getting fairer and more representative districts, he explained, “we know that the right community will receive an appropriate amount of population-based funding.’

Pocan’s argument carried the day. The amendment was approved by a voice vote and included in the final measure, which passed the House Friday on a 234-193 party line vote. The fight is far from finished. Senate majority leader Mitch McConnell, the Kentucky Republican who makes no secret of his disdain for campaign-finance reform and the expansion of voting rights, is already erecting roadblocks to the measure.

“Majority Leader McConnell should listen to the American people, stop his dishonest attacks on this bill, and bring it up for a vote in the Senate,” says Pocan, even as he warns that: “Republicans are against expanding the right to vote, ensuring transparency, and reforming our democracy because they know that a corrupt system is the surest way for them to win.”