In the past few months, several countries have announced plans to eliminate the bags. Bangladesh and some African nations have sought to ban them because they clog fragile sewerage systems, creating a health hazard. Starting this summer, China will prohibit sellers from handing out free plastic shopping bags, but the price they should charge is not specified, and there is little capacity for enforcement. Australia says it wants to end free plastic bags by the end of the year, but has not decided how.

Efforts to tax plastic bags have failed in many places because of heated opposition from manufacturers as well as from merchants, who have said a tax would be bad for business. In Britain, Los Angeles and San Francisco, proposed taxes failed to gain political approval, though San Francisco passed a ban last year. Some countries, like Italy, have settled for voluntary participation.

But there were no plastic bag makers in Ireland (most bags here came from China), and a forceful environment minister gave reluctant shopkeepers little wiggle room, making it illegal for them to pay for the bags on behalf of customers. The government collects the tax, which finances environmental enforcement and cleanup programs.

Furthermore, the environment minister told shopkeepers that if they changed from plastic to paper, he would tax those bags, too.

While paper bags, which degrade, are in some ways better for the environment, studies suggest that more greenhouse gases are released in their manufacture and transportation than in the production of plastic bags.

Today, Ireland’s retailers are great promoters of taxing the bags. “I spent many months arguing against this tax with the minister; I thought customers wouldn’t accept it,” said Senator Feargal Quinn, founder of the Superquinn chain. “But I have become a big, big enthusiast.”

Mr. Quinn is also president of EuroCommerce, a group representing six million European retailers. In that capacity, he has encouraged a plastic bag tax in other countries. But members are not buying it. “They say: ‘Oh, no, no. It wouldn’t work. It wouldn’t be acceptable in our country,’ ” Mr. Quinn said.