Economic sanctions work roughly a third of the time. The largest systematic study, covering 174 cases, judged sanctions at least partially successful in about 34 percent of episodes — but whether that counts as “working” depends heavily on what the sanctions were trying to achieve, because the success rate varies enormously by goal. The honest answer is neither the dismissal that sanctions never work nor the assumption that pressure eventually tells; it’s that they work under specific conditions that are often absent in the cases that get the most attention.

Where the one-in-three figure comes from

The standard reference is the Peterson Institute for International Economics database assembled by Hufbauer and colleagues, covering 174 case studies and 204 observations running through 2007. Episodes are scored from 1 to 16, combining how far the policy goal was achieved with how much the sanctions themselves contributed. A score of 9 or higher counts as at least partially successful, and about 34 percent of cases clear that bar.

What that 34 percent actually means

This is where most citations of the number go wrong, and the study’s own authors are careful about it. A score of 9 doesn’t mean sanctions achieved a foreign policy triumph — it means only that sanctions made a modest contribution to a goal that was partly realized. The 34 percent figure measures partial contribution to partial success, not targets capitulating.

Success depends enormously on the goal

Aggregate rates conceal the most useful finding: sanctions are far better at small asks than large ones.

• Modest policy changes: 51 percent success.
• Regime change and democratization: 31 percent.
• Military impairment: 31 percent.
• Disrupting minor military adventures: 21 percent.

The pattern is intuitive once stated. Asking a government to release a prisoner or adjust a policy is a cost-benefit calculation it can make. Asking it to dissolve itself is not, because no amount of economic pressure outweighs the survival of the people making the decision.

What makes sanctions more likely to work

Several conditions separate the successes from the failures, and most are visible before sanctions are even imposed. Economic leverage is decisive: where bilateral trade is 10 percent or more of the target’s GDP, the success rate is about 50 percent, while where it’s under 2 percent, the failure rate is around 80 percent. Successful cases imposed costs averaging 3.3 percent of the target’s GNP, against 1.6 percent in failures. Regime type matters too — sanctions against a democracy are roughly twice as likely to succeed as sanctions against an autocracy, because autocratic leaders can insulate themselves from economic pain and pass it downward instead. Prior relationship plays a role as well: sanctions against former allies with cordial prior relations do better, while against antagonistic targets, success falls to about 19 percent. And comprehensive packages combining financial, export and import measures succeed around 40 percent of the time, with imposing them quickly beating escalation in increments, which just gives the target time to adapt.

What makes them fail

Duration is the clearest warning sign, and it runs opposite to intuition. Successful episodes lasted 4.4 years on average; failures lasted 8.4 years, and around two-thirds of successful sanctions achieved their goal within three years. Long-running sanctions aren’t pressure slowly accumulating — they’re usually evidence that the pressure didn’t work and that the target has adjusted, found new trading partners, or restructured around the restrictions. Offsetting assistance from a rival power undoes the leverage directly, and so does a target economy with little exposure to the sender in the first place.

Are sanctions getting more effective over time?

Somewhat. Comparing periods within the same database, success rates rose from around 32 to 34 percent before 1990 to roughly 39 to 40 percent afterward — an improvement of about a fifth. The usual explanation is the post-Cold War shift toward targeted measures aimed at named individuals and entities, such as asset freezes and travel bans, rather than economy-wide embargoes. The UN describes its own regimes as including arms embargoes, travel bans, financial restrictions and commodity restrictions, imposed under Article 41 of the Charter, which covers enforcement measures that don’t involve the use of armed force.

Why the numbers deserve some caution

One caution belongs on every figure above. Judging whether sanctions actually caused an outcome means comparing the world as it happened with a world that didn’t occur, and scholars disagree about how cases in this database are coded — the 34 percent figure has been contested in both directions. Sanctions also serve purposes a success rate doesn’t capture, including signaling resolve, constraining a target’s capabilities rather than changing its mind, and satisfying a domestic demand to do something short of war. The defensible conclusion is narrower than either side of the public argument: sanctions can work, they work best on limited goals against economically exposed and politically accountable targets, and the longer they run, the less likely they are to be the reason anything actually changes.