Mary Ellen O'Connell

August 07, 2026

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News Aug. 5, “There is no peace now in Gaza, and there has been no peace since President Trump announced a ceasefire in October 2025. Instead, Israel has slowed the pace of its air attacks in general. The attacks have increased again, and slowed, but never stopped,” she said. “On Sunday, Israeli attacks killed an estimated 18 Palestinians. That is not peace. Israeli ground troops have pulled back from some positions but not to the positions agreed.”

June 22, 2026

In written comments shared with OSV News, Mary Ellen O'Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, said, "even in this preliminary form," the MOU "demonstrates the folly of unlawful war. The MOU reflects the high price the U.S. is willing to pay to reverse the violation of the United Nations Charter committed together with Israel on February 28," she said. "The MOU reflects Iran's demands more than the U.S.'s war goals. There is nothing, for example, requiring the Iranian authorities to hold elections or in any way promote the rule of law and respect for human rights. There is no hint the government will be anything other than the successors of the 1979 Islamic Revolution. President Trump declared he would crush that regime."

June 16, 2026

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, said she is “a bit more optimistic” about the development than Trump’s other claims that an end to the months-long conflict was near. “He has associated the current effort with his birthday and his trip to Europe – he very much wants a success,” she said. “He is also coming under increased pressure from his party and his base to end the unpopular, damaging war.”  However, O’Connell cautioned that “major obstacles to a deal” remain, including a lack of trust between the parties and Israel’s ongoing war in Lebanon against Hezbollah, a Lebanese Shiite militia allied with Iran. “Iran appears to be in a position to continue at the current pace without assurances in both instances,” she said. “The way to rebuild trust is through a staged approach. The U.S., might for example, offer a good faith assurance through an initial large release of assets. If Iran takes commensurate steps to open the straits, allow in demining technology, and the like, the next release can occur.”

April 16, 2026

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, said in comments to OSV News that Vance “has suggested Pope Leo needs to re-acquaint himself with Catholic theology respecting peace and war. In fact, Pope Leo’s every comment on the wars raging at this time have been wholly consistent with Catholic teaching and consistent with international law.” 

April 08, 2026

Mary Ellen O’Connell, professor of law and international peace studies at the University of Notre Dame’s Kroc Institute, told OSV News that Trump’s April 7 statement and previous threats contravene key legal instruments such as the Geneva Conventions and possibly the Genocide Convention.

March 02, 2026

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, argued in written comments shared with OSV News that “February 28, 2026, will forever mark the day that the United States began a war on Iran that will be compared with the disastrous March 2003 invasion of Iraq. Like Iraq, this war egregiously violates the prohibition of force,” O’Connell said. “This is international law’s most fundamental principle. The violation in Iraq’s case turned out to be the U.S.’s worst foreign policy decision ever. The war on Iran may turn out to be worse.”

January 05, 2026

Although “the president of Venezuela has committed serious violations of human rights for years,” the international legal system “has appropriate ways of responding in such cases” that begin “by supporting the rule of law in Venezuela,” said Mary Ellen O’Connell, professor of law and international peace studies at Notre Dame.

October 30, 2025

Mary Ellen O'Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, said in comments shared with OSV News, "Israel's decision to bomb is an unjustified breach of its commitment to the ceasefire. There have been issues but nothing serious enough to justify this violation."

October 21, 2025

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News, “From the first reports of the United States Navy destroying small boats in the Caribbean, I have had the gravest of concerns. The use of military force in such circumstances simply cannot be justified under international human rights law or the law of armed conflict,” she said. “Among the many reasons why the attacks are unlawful, the U.S. does not have sufficient facts about who is on the boats. Reports that a fisherman from Colombia has been killed underscores that major issue.” As his country’s president, O’Connell said, Petro “has a duty to protect his citizens by protesting their unlawful killing.”

October 08, 2025

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News, “Any movement toward peace, release of the Israeli hostages, and emergency aid for Gazans is welcome.”

August 19, 2025

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, said, “Europe understands both the moral importance of upholding law as fundamental as the prohibition on the use of force, and the danger of emboldening someone like Putin.” 

July 23, 2025

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, expressed concern about the decision. “Leaving UNESCO will deal another blow to the reputation of the United States as a world leader in what matters–peace, human rights, health, the environment, and now culture,” she told OSV News.

June 23, 2025

“If diplomacy is possible, war is unlawful,” Mary Ellen O’Connell, professor of law and international peace studies at the University of Notre Dame, told OSV News. “Diplomacy is needed now more than ever to end the senseless bloodshed throughout the Middle East. While Iran is correct that it is the victim of a grave breach of international law, it has no right to retaliate merely for the sake of revenge.”

June 16, 2025

Mary Ellen O'Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News that "times of transition such as this -- for the church, for states, for technology -- offer both risk and opportunity."

April 25, 2025

“I have had concerns over the years about State Department activities that promoted idiosyncratic American policies on democracy, human rights — including religious liberty and war — policies not in line with international law,” Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News.

July 29, 2024

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News that in navigating foreign policy, “we are fortunate as Catholics to have the wisdom and insights of Pope Francis on major issues of the day.” Daniel Philpott, professor of political science at Notre Dame, told OSV News Harris would likely “continue the foreign policy of the Biden administration and would prompt the same combination of convergence and contradiction with the social teachings of the Catholic Church that Biden’s policy created.”

April 17, 2024

Mary Ellen O’Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News that “the clear success in countering Iran’s missile and drone strikes on Israel is a dramatic demonstration of the true legal and moral meaning of ‘self-defense.'”

January 04, 2024

The question is being asked: Can Israel’s conflict conduct be considered a “just war” under the Catholic understanding of the concept? Mary Ellen O’Connell, a professor of law and international peace studies at the University of Notre Dame in Indiana, told OSV News that’s the wrong question.

November 15, 2023

“We need to beef up our State Department. We need skills for diplomacy,” said Mary Ellen O’Connell, a law professor and professor of international peace studies at the University of Notre Dame’s Kroc Institute. “

September 13, 2023

Mary Ellen O'Connell, a professor at Notre Dame Law School who specializes in international law and conflict resolution, told OSV News that "the Catholic Church is in full support of the total ban on cluster munitions" due to its effects on civilians, including long after the conflict.