The Supreme Court did not address those questions directly, of course, but its decisions impact how we define ourselves as a nation through our laws. And on affirmative action, voting rights and federal and state marriage law, the Supreme Court’s answers were troublingly mixed. If nothing else, the aftermath reveals just how much work is left to do to build that more perfect union.

Affirmative action and the Voting Rights Act of 1965 not only helped dismantle the stone wall of discrimination and the maze of injustice constructed during centuries of slavery and legal segregation, they continue to keep clear the path to the polls and to keep fertile the field of opportunity. At least, they did — until this week.

During the middle decades of the 20th century, the civil rights movement, and elected leaders who were “Profiles in Courage” in their own right, helped usher in a new era. Those of us who grew up in that era witnessed breathtaking historical changes — changes that often moved us to tears. For some, the 2008 election of our nation’s biracial president was a culmination; for others, a beginning. Truly though, it was both.

As a young African-American woman, I watched Dr. Martin Luther King Jr. and other human rights leaders fight — and too often die — to correct the injustices of the past. Their eventual legislative triumphs proved to a nation divided that this country could come together to do big things and seek our better angels.

But in two separate rulings, the Court jeopardized that legacy and weakened the power of this country to fix injustice. The conservative Justices struck down a key portion of the Voting Rights Act — in part because it had been too successful at tackling the discriminatory barriers to the ballot it had been written to correct. And the justices sent a significant case challenging affirmative action policies back to a lower court, inviting intense scrutiny upon a policy that has helped make our colleges and universities more diverse, dynamic and representative places to learn and grow.

Most people don’t realize we don’t have a constitutional right to vote. True, the 15th, 19th and 26th amendments prohibit discrimination based on race, sex or age, but the chaos that has accompanied so many elections — federal, state and local — since 2000 indicates it may be time to consider an amendment to standardize the voting process and to provide protections against disenfranchisement. Maybe it’s time for a Right to Vote Amendment.

In the other two cases, one challenging the so-called Defense of Marriage Act and the other California’s Proposition 8 ban on marriage equality, the Supreme Court again brought out the red pen. But this time it struck down discriminatory laws — laws that were enacted at a time when the majority of Americans still saw LGBT people as strangers, even a threat. Now that these laws are gone, the LGBT movement hopes to secure corrective legislation of its own — guaranteeing workplace non-discrimination and national federal recognition of same-sex marriage.

When these four rulings are taken together, they provide a powerful lesson about how all movements for justice are linked. The LGBT community should look to the rulings on affirmative action and voting rights and see that certain ideologies will always be hostile to minority groups seeking to chart a better future. And African-American, Hispanic and other ethnic minorities should look to these victories for marriage equality and see echoes of their own history — and embrace a shared struggle.

Our nation must better itself. It always has, and now we must continue anew. The Supreme Court makes a lot of noise. Sometimes it sings in harmony with history, and sometimes it caws against it. It would do well to remember that the melody of freedom is heard in the choir of the people.

At its best, the Supreme Court can help guide our journey, following the course charted by our founding documents. It can correct us when we stray as a nation. But it can also be profoundly wrong.

Ultimately, it is the American people who must decide what kind of nation we hope to be. Justice Antonin Scalia, Justice Thurgood Marshall, Dr. King and Harvey Milk were all citizens alike. And even after a week like this, it’s only together that we can do what’s right.

Donna Brazile is a senior Democratic strategist, a political commentator and contributor to CNN and ABC News, and a contributing columnist to Ms. Magazine and O, the Oprah Magazine.