Here’s a toast to the people of Ireland who may have stopped Europe’s slide into a regulatory morass — for now — by voting “no” on the Lisbon Treaty, which would enlarge the power of European Union bureaucrats and would weaken the role of member governments.

Europeans and Americans should be grateful for Thursday’s vote, but mindful that the Eurocrats are intent on pushing through the treaty, even if they have to change their rules to do so.

Since E.U. rules require unanimous approval, the Irish “no” makes the treaty’s future uncertain. The treaty was approved by 18 of the 27 member governments without a referendum, perhaps because the governments suspected that a popular vote would be negative. Britain could ratify the treaty as early as tomorrow, and remaining countries could follow.

Americans should care about the treaty because our country and the 27-member E.U. form the largest bilateral trade relationship in the world, with America importing more than $500 billion and exporting almost $425 billion in 2007.

Anything that Europe does to undermine its own economic growth hurts America because we would sell fewer goods to a weaker continent. That means fewer jobs for Americans who work in exporting companies.

For this reason, it matters to America that the Lisbon Treaty would take Europe too far down the road toward supranationalism. Signed in 2007, the treaty was the result of efforts to salvage parts of a proposed European Constitution, which was rejected by referenda in Holland and France in 2005.

Proponents of the treaty say that harmonizing national laws, especially in matters affecting business and trade, brings substantial advantages to all, and that a politically unified E.U. would be better able to compete economically and expand to include other countries, such as the Ukraine.

Half a century after the 1957 Treaty of Rome created a six-nation Common Market in Europe, Europe has achieved substantial economic integration. What is in play now is political integration, delegating to the E.U. more of the powers that national governments exercise. Doing that may take the idea of “Europe” too far, as a majority of Irish voters signaled on Thursday.

Many Europeans approve of the economic free trade zone, but don’t appear to want a treaty that increases the influence of the E.U. bureaucracy and reduces the political power of individual countries. Fifty-five percent of the French, the most pro-E.U. country in Europe, voted against the European constitution in 2005. The emotions over the current Euro Cup soccer matches show that national identity is alive and well.

Here are some of the consequences that the Lisbon Treaty would spawn: The new president of the European Council would be an individual with a 30-month term, rather than a member government with a six-month presidential term. The size of the E.U.’s executive body, the European Commission, would be reduced from one commissioner from each of the 27 countries to 18 commissioners in total: In each 15 year period, every country would experience five years without representation.

A new post, the High Representative of the Union for Foreign Affairs and Security Policy — a de facto foreign minister — would be created to represent the E.U. in world bodies, potentially overriding the foreign ministers of the member states.

America should care about this because individual European countries would be prevented through an E.U. regulatory burden from trading with us, both through more sluggish economies and in more protectionist policies pursued by the E.U. Parliament. The treaty removes the abilities of member nations to innovate and pursue paths to economic prosperity.

Member countries would lose the right to establish trade agreements with non-E.U. governments covering services and foreign direct investment. New regulations would alter American bilateral agreements with countries such as Britain.

Under Lisbon, the European Court of Justice could expand its power to interpret European law and interfere with what were previously internal matters. Depending on the interpretation taken by the courts, E.U. competitiveness could be hurt by adverse rulings on strikes, health care, or migrants’ rights to social security and other assistance. This would slow E.U. growth, reducing European purchases of American goods — and harming American employment.

The treaty would require members to coordinate their economic and social policies even more than at present, chaining the more dynamic nations, preventing growth which would help drive the world economy. By establishing a central policy of combating climate change, or ridding Europe of “harmful” chemicals, the treaty limits our export potential.

The treaty’s supporters have not given up. They can be expected to try to change E.U. rules so Ireland’s voters cannot frustrate the drive toward greater European integration and supranationalism.

But perhaps Irish voters know better and their vote should be respected.

Ms. Furchtgott-Roth, former chief economist at the U.S. Department of Labor, is a senior fellow at the Hudson Institute. She can be reached at dfr@hudson.org.