Lord Salisbury, who served as British foreign secretary in the late 1800s, observed that “the commonest error in politics is sticking to the carcass of dead policies.” As Barack Obama enters the White House, several venerable U.S. policies reek of decay. Three policies are especially in need of burial during the new president’s first months in office.

One is our attempt, now about to enter its sixth decade, to isolate Cuba. Whatever the rationale for that policy during the cold war, when U.S. leaders regarded Fidel Castro’s regime as a Soviet stooge and a dangerous, disruptive influence throughout the Western Hemisphere, the justification became far weaker once the Soviet Union collapsed. Moreover, even during the cold war, the attempt to isolate Cuba did not work terribly well. Much of the international community, including Canada and many of America’s other close allies, gradually abandoned support for Washington’s approach and pursued substantial diplomatic and economic relations with Havana. That trend has accelerated in the post-cold war period.

The U.S. economic embargo has damaged the Cuban people, since the loss of the American market made a country already impoverished by the idiocies of Marxist economics even poorer. It has not, however, brought down the communist system or even seriously inconvenienced Cuba’s political elite. Indeed, it has given the communist regime the perfect scapegoat for the country’s chronic economic failures, thereby muting potential domestic opposition.

After nearly half a century of policy failure, it is time to try a different tack. Much of Washington’s Cuban policy has not even been guided by rational foreign-policy considerations. Instead, it has been a product of domestic political calculations, specifically the perceived need to placate the vehemently anticommunist Cuban-American community in Florida and a few other states that have crucial blocs of electoral votes in U.S. presidential elections.

But times have changed and so should our policy toward Cuba. Raúl Castro’s emergence as the country’s new leader has already led to signs of pragmatism and perhaps the prospect of serious economic reforms. In the United States, a significant portion of the Cuban-American community is now supportive of engagement rather than isolation toward the island. That attitude is especially strong among younger Cuban Americans. Most important, Cuba is no longer a geopolitical pawn that can be exploited by a superpower rival of the United States. The Obama administration should commence negotiations with Havana to restore diplomatic relations, and Obama himself should push Congress to liberalize, if not revoke, the system of economic sanctions.

Washington’s policy of trying to make Iran a pariah has been in place for thirty years, rather than the half century with regard to Cuba, but it is equally misguided. The Islamic regime in Tehran is among the world’s most repressive governments and a notorious state sponsor of terrorist movements, but as in the case of U.S. policy toward Cuba, the attempt to isolate Iran has largely failed. True, the Bush administration has induced the UN Security Council to impose economic sanctions in response to Tehran’s nuclear program, but key countries, including such prominent U.S. allies as France and Germany, maintain significant investment and trade ties with Iran.

Whether U.S. policymakers like it or not, Tehran is a major power in the Middle East, and it will play an important role in several arenas. As Iraq’s neighbor, Iran is going to have extensive influence in that country, especially among its Shiite coreligionists that make up 60 percent of Iraq’s population and control the Baghdad government. There will be little stability in Iraq following the drawdown of U.S. forces without Tehran’s cooperation. Likewise, the prospects for stability in Lebanon or progress in the Israeli-Palestinian conflict require a constructive posture by Iran. Even the U.S. mission in Afghanistan could become even more precarious than it is now if Iran decides to mute its previous hostility toward the Sunni militants of al-Qaeda and the Taliban.

The Obama administration should launch an effort to normalize relations with Iran. That means a willingness to negotiate without preconditions on a wide range of issues—not only the nuclear program, but also Iran’s overall position in Iraq and its policies throughout the Middle East. Such a shift in strategy necessitates U.S. acceptance of Iran as a significant regional player, and a tacit admission that the current U.S. policy is obsolete and counterproductive.

The final rotting policy carcass is America’s drug war—both its domestic and international phases. U.S. leaders have adhered to a prohibitionist policy since the enactment of the Harrison Act in 1914, and they have pursued an intensified effort to stamp out drug trafficking and drug use since Richard Nixon declared a “war” on drugs at the beginning of the 1970s.

Drug prohibition is yet another long-standing policy that has produced few positive results. Despite the expenditure of hundreds of billions of dollars and the creation of a vast drug-war bureaucracy at the federal, state and local levels, the rates of illegal drug use are higher now than when Nixon launched his crusade. Meanwhile, we have filled our prisons with drug-law violators, at an enormous cost to taxpayers. More than 60 percent of inmates in federal prisons and roughly a third of inmates in state prisons are in for drug offenses. The huge black-market profit resulting from prohibition has led to violent turf fights between rival drug gangs in numerous American cities.

The international component of the drug war has produced equally perverse results. Washington both bribes and pressures the governments of drug-source nations—especially Colombia and the other Andean countries, Mexico and Afghanistan—to wage war on the drug trade. As on the domestic front, the lucrative black-market premium guarantees that the trade will be dominated by ruthless criminal elements, who use their vast resources to corrupt or intimidate government officials. Washington’s effort to stem the supply is now in its fourth decade of failure. For example, despite spending more than $5 billion over eight years on Plan Colombia—the program to eradicate drugs in the Andean region—a recent GAO report confirmed that the amount of cocaine, the region’s principal drug export, has actually increased. The same is true for a variety of drugs coming out of Mexico.

The drug war is both cruel and futile. Prohibition did not work with regard to alcohol in the 1920s and early 1930s, and that strategy is not working with regard to marijuana, cocaine and other illegal drugs today. President Obama should order a comprehensive policy reassessment.

It is hard to cast off the heavy carcass of dead policies. But one of the virtues of a presidential election and the start of a new administration is that it creates the opportunity for fresh ideas. Instead of being burdened by policies that have failed for decades and show no realistic prospects of succeeding in the future, President Obama should conduct some long overdue burials.