In 1819, Dartmouth faced a critical legal challenge when its charter was amended to make it a public institution. The College's board, led by Dartmouth alumnus Daniel Webster(Class of 1901), took Trustees of Dartmouth College v. Woodward to the Supreme Court of the United States. In a landmark decision, Chief Justice John Marshall ruled in favor of Dartmouth, affirming its status as a private institution. The case has since become a cornerstone of U.S. constitutional and corporate law. Webster, who refined his debate skills as a member of the United Fraternity literary society, is remembered for his impassioned defense of Dartmouth, stating, “It is, Sir, as I have said, a small college. And yet there are those who love it.”

In the mid-19th century, The Society of Social Friends emerged as a key forum for debates on slavery. The Society played a pivotal role in fostering discussions on the fugitive slave bill and other contemporaneous issues. The robust exchange of ideas on campus had an enduring impact on students, many of whom broadened their perspectives. Jonathan C. Gibbs, a member of the Society of Social Friends and Class of 1852, became Florida's first black Secretary of State during the Reconstruction period.

In 1947, President John Sloan Dickey (Class of 1929) introduced Dartmouth’s transformative "Great Issues" course, which ran until 1966. This pioneering curriculum brought esteemed speakers like Robert Frost and Thurgood Marshall to campus, engaging seniors in discussions on pressing national and international topics. Despite initial acclaim, the course faced criticism from students as burdensome and dull, and the course eventually ended. As Professor James Murphy has noted, speakers rarely debated each other and the speaker list lacked political, racial, and religious diversity.

As McCarthyism, the political persecution of alleged communists by Senator Joseph McCarthy, cast a shadow over the nation, U.S. President Dwight D. Eisenhower spoke out against censorship in his historic 1953 commencement address at Dartmouth College. President Eisenhower urged students not to join "the book burners" and emphasized the importance of exploring diverse perspectives. His unscripted address signaled a behind-the-scenes battle between the President and Senator McCarthy, and his remarks influenced subsequent policy changes in the U.S. State Department regarding the removal of books from U.S. overseas libraries. President Eisenhower’s commencement address marked a significant moment in the fight against McCarthyism and censorship in American society.

In 1962, Dartmouth College hosted an influential lecture by Reverend Dr. Martin Luther King, Jr. as part of the “Great Issues” course. His first visit was canceled due to an unexpected indictment from the state of Alabama on charges of tax evasion. His second visit coincided with mass rioting in the South, prompting him to cut his Dartmouth events short and return to lead the Freedom Rider movement. Despite the challenges, on May 23, 1962, Dr. King electrified the audience in an overflowing 105 Dartmouth Hall, discussing the rampant racism in the American South and the broader inequalities faced by African Americans. His impactful remarks left a lasting impression on the Dartmouth community and the Upper Valley and contributed to the ongoing struggle for civil rights.

In January 1986, Dartmouth faced upheaval following a controversial incident where students, largely associated with a conservative campus newspaper, The Dartmouth Review, destroyed shantytowns protesting apartheid in South Africa. The destruction caused students from Dartmouth Community for Divestment and the Afro-American Society to occupy Parkhurst Hall for 30 hours, demanding a ‘one-day moratorium classes to discuss racism, sexism, and the right of dissent.’ President David T. McLaughlin (Class of 1954) and the faculty’s executive committee suspended classes on a Friday, marking the first suspension of classes for a teach-in since the 1960s. Faculty, staff, students, and President McLaughlin engaged in a campus wide discussion on racism, violence, and diversity on January 24, 1986.

In his 2002 convocation address, President James Wright affirmed the critical importance of open debate and dialogue on campus. Amid campus discussions on terrorism, civil liberties,and the Israeli-Palestinian conflict, President Wright underscored the need for respectful and constructive debate. He highlighted the importance of avoiding both shameful speech and shameful silence, promoting an environment that welcomed the challenge of ideas. Excerpt: “Debate means listening as well as speaking, and here it leaves no place for intimidation,for anti-Semitism, for anti-Muslim and anti-Arab attitudes, for racism, or for impugning the patriotism of those who challenge prevailing wisdom... The best debate is the one that tests ideas rather than asserts them.”

In 2009, a previous iteration of the Dartmouth Political Union was established by Nathan Bruschi '10, Brice Acree '09, Tay Stevenson '10, Daniel J. Thele '10, and Maryam Zafer ’12. This version of the DPU held formal debates with the aim of promoting discourse on campus.

In 2018, undergraduates William Reicher ’22 and Vlado Vojdanovski ’22 established the Dartmouth Political Union in its current form. Motivated by the divisive reactions to a campus visit by conservative commentator David Horowitz, Reicher and Vojdanovski aimed to create a non-partisan student organization that fostered open discourse across the political spectrum. Today, we at the DPU root our mission in the rich historical legacy of freedom of expression and dissent on campus.