- European Union Expands (May 1): Ten countries join, bringing number of member nations to 25.
- Foreigners Killed in Saudi Arabia (May 1): Two Americans, two Britons, and an Australian die when gunmen open fire in an engineering office in Cairo.
- Likud Party Rejects Sharon's Gaza Plan (May 3): Israeli prime minister's party votes down his proposal to withdraw settlers and soldiers from the Gaza Strip.
- New Iraqi Commander Takes Over in Falluja (May 3): Muhammad Latif replaces Jasim Muhammad Saleh, who was a high-ranking member of Saddam Hussein's Republican Guard.
- Shiites Demand Rebel Cleric Withdraw Forces (May 4): About 150 influential leaders meet in Baghdad and urge Moktada al-Sadr to hand over weapons and remove his militia from Najaf and Karbala. (May 27): U.S. agrees to withdraw from Najaf and suspend the arrest warrant for al-Sadr, who agrees to pull his militia off the streets.
- Bush Addresses Prison Abuse (May 5): In interviews on Arab television, president calls abuse and deaths of Iraqi prisoners “abhorrent.” Bush upbraids Secretary of Defense Donald Rumsfeld for not informing him about the photos earlier.
- American Arrested in Madrid Bombing Case (May 6): Oregon lawyer Brandon Mayfield detained on a material witness warrant.
- American Decapitated in Iraq (May 8): Videotape broadcast on an Islamist website shows murder of Nicholas Berg, a 26-year-old businessman. Jordanian militant Abu Musab al-Zarqawi believed to be responsible.
- Bomb Kills Chechen President (May 9): Akhmad Kadyrov, a former rebel leader who was elected in late 2003, and 13 others die in Grozny.
- Israeli Troops Raid Gaza (May 11): Palestinian attack on an armored vehicle kills six Israeli soldiers searching for weapons facilities. Israelis return fire, killing several Palestinian militants. Palestinians confiscate body parts of slain Israelis. (May 13): In Egyptian-brokered deal, Palestinians return remains of Israeli soldiers in exchange for Israeli withdrawal of troops. (May 18): In pursuit of Palestinian militants and weapons, Israeli troops raid Palestinian neighborhood in Gaza Strip, killing about 20.
- Bush Imposes Sanctions on Syria (May 11): Places economic restrictions on trade with Syria, citing its failure to reign in terrorist groups.
- India's Prime Minister Resigns (May 13): Indian National Congress Party prevails in parliamentary elections. Premier Atal Bihari Vajpayee steps down.
- Court Dismisses Impeachment of South Korean President (May 14): Constitutional Court ruling reinstates Roh Moo Hyun as president.
- Iraqi Leader Killed (May 17): Ezzidin Salim, president of the Iraqi Governing Council, is killed by a suicide bomber in Baghdad.
- Gandhi Refuses to Become Prime Minister (May 18): Sonia Gandhi, leader of the Indian National Congress Party, announces she will not become premier. Former finance minister Manmohan Singh is named to the post.
- Nigerian President Declares State of Emergency (May 18): Olusegun Obasanjo moves to stem sectarian violence in state of Plateau, site of deadly battles between Christian and Muslim militias.
- U.S. Soldier Sentenced in Abuse Scandal (May 19): In the first court-martial in the prisoner abuse scandal in Iraq, Spc. Jeremy Sivits pleads guilty to several charges.
- Iraq Disputes U.S. Attack (May 19): U.S. says attack that killed more than 40 people targeted a safehouse that sheltered foreign fighters. Iraqis claim victims were part of a wedding celebration.
- Israelis Open Fire on Protest (May 20): Nearly 40 killed—many of them civilians and children—when helicopter gunship attacks protest march in Gaza Strip. Israeli tanks bulldoze more than 100 homes in a Gaza neighborhood. UN Security Council passes a resolution condemning actions.
- U.S. Raids Office of Former Iraqi Ally (May 20): U.S. troops and Iraqis confiscate computers and ransack headquarters of Ahmad Chalabi, a member of the Iraqi Governing Council who had been receiving a monthly stipend from the U.S. government.
- Roof Collapses at Airport in France (May 23): At least five killed at new terminal at the Charles de Gaulle airport near Paris. Authorities blame faulty construction.
- Army Report Reveals Widespread Prison Abuse (May 25): Document, dated May 5, indicates abuse started in Afghanistan in late 2002 and lasted until April 2004.
- Sudan Rebels and Government Reach Accord (May 26): Islamic government and Sudan People's Liberation Army agree to end civil war that has lasted more than 20 years and claimed about two million people. However, war in western Darfur region between Arab militias and black Africans continues unabated.
- Prime Minister of Iraq Chosen (May 28): Former exile and member of the Iraqi Governing Council Iyad Allawi will serve as interim premier.
- Guantánamo Interrogators Sent to Iraq Prisons (May 28): U.S. military officials acknowledge that interrogation experts advised intelligence gatherers at the Abu Ghraib prison.
- Militants Attack Residential Area of Saudi Arabia (May 29): Gunmen open fire on Khobar complex that houses Americans and other foreigners and take several hostages. (May 30): Saudi commandos free most of the hostages and capture several militants.
- Senate Opposes New Overtime Rules (May 4): Votes, 52–47, against Labor Department plan to revise regulations on overtime pay.
- Pentagon Revises Plan to Reduce Number of Troops in Iraq (May 4): Defense Department announces 135,000 U.S. soldiers will remain in Iraq through 2005. Earlier plan said number would be reduced to 115,000 by the end of May 2004.
- White House Requests More Money for Iraq (May 5): Administration seeks an additional $25 billion for the military budget.
- FDA Rejects Morning-After Pill (May 6): Food and Drug Administration disregards the opinion of its expert advisory panel and bans over-the-counter sale of emergency contraception drug.
- Rumsfeld Acknowledges Abuse in Iraq (May 7): At hearings before the Senate and House Armed Services committees, secretary of defense apologizes to Iraqis who endured torture by members of the U.S. military. He also announces that a panel will investigate the abuse. (May 10): Despite increasing number of calls for Rumsfeld to resign, President Bush throws his support behind the beleaguered secretary of defense, saying You are doing a superb job. You are a strong secretary of defense, and our nation owes you a debt of gratitude.
- Justice Department Reopens 1955 Murder Case (May 10): New evidence introduced by documentary filmmakers into murder of 14-year-old Emmett Till prompts officials to reinvestigate the civil rights era case.
- Members of Congress View Additional Photos (May 12): Lawmakers view an additional 1,800 pictures and video images of abuse of Iraqi prisoners. Many say they are more gruesome and explicit than those previously made public.
- FEC Allows Campaign Spending (May 13): Federal Election Commission refuses to limit spending by independent political committees, known as 527 organizations.
- Bush Administration Alters AIDS Drug Policy (May 16): Changes expedite process for approving generic and combination antiretroviral drugs. Plan will allow countries in Africa and the Caribbean to buy drugs at lower prices.
- Gay Marriages Begin in Massachusetts (May 17): Dozens of same-sex couples marry in Massachusetts, the first state in the country to legalize such unions.
- White House and Senate Agree on Judicial Nominees (May 18): Bush administration agrees to end recess appointments of judges. Senate Democrats agree to confirm nomination of 25 judges, but will continue to block confirmation of 7 other nominees.
- Sept. 11 Panel Criticizes New York's Infrastructure (May 18): Commission investigating the attacks reports that efforts of police and fire departments were compromised by interagency communication problems and rivalries.
- Bush Outlines Iraq Plan (May 24): Five-step plan to build a secure and democratic Iraq includes handing over authority to a sovereign government; helping to establish stability and security; continuing to rebuild infrastructure; encouraging more international support; and moving toward free elections.
- Oklahoma Bombing Accomplice Convicted in State Court (May 26): Terry Nichols found guilty of 161 counts of first-degree murder. He had been convicted in federal court.
- Court Upholds Assisted Suicide Law (May 27): Saying the federal government can't intervene in state law, a federal appeals court rules that the justice department does not have the authority to penalize doctors who help terminally ill patients commit suicide.
- New World War II Memorial Dedicated (May 29): About 200,000 people, including almost 100,000 veterans, attend the Washington, DC, dedication of the National World War II Memorial.
- Picasso Work Sold for Record Price (May 5): Pablo Picasso's Boy with a Pipe sells for $104.1 million at a Sotheby's auction.
- Economy Adds Jobs (May 7): Labor Department reports creation of 288,000 jobs in April. Unemployment rate drops to 5.6% from 5.7% in March.
- Bush Renominates Greenspan (May 18): President asks chairman of the Federal Reserve to serve a fifth four-year term. Senate confirmation expected.
- Violent Crime Decreased in 2003 (May 24): FBI's annual report indicates violent crimes dropped by 3.2%. Murder, however, increased by 1.3%.
- Boston Archdiocese to Shutter Churches (May 25): Almost 20% of the Roman Catholic churches in the Boston Archdiocese will close by the end of 2004.
- Aspirin May Prevent Breast Tumors (May 26): Report in the Journal of the American Medical Association shows that women who take aspirin at least seven times a week are 26% less likely to develop a certain kind of tumor than women who did not take it.
- Floods Devastate Caribbean Island (May 26): Death toll reaches 1,950 from floods caused by days of heavy rains in Haiti and the Dominican Republic.
- List of Smoking-Related Illnesses Grows (May 27): In addition to lung and larynx cancer and bronchitis, report by Surgeon General says smoking can also cause cervical, kidney, pancreatic, and stomach cancer, in addition to other serious diseases.