PARIS — European activists who participated in American Internet protests last month learned that there was political power to be harnessed on the Web. Now they are putting that knowledge to use in an effort to defeat new global rules for intellectual property.

In the U.S. protests, Web sites including Wikipedia went dark Jan. 18, and more than seven million people signed Google’s online petition opposing the Stop Online Piracy Act and the Protect Intellectual Property Act. Ultimately, even the bills’ sponsors in the U.S. Congress backed down under the onslaught of public criticism.

The European activists are hoping to use similar pressure to stop the international Anti-Counterfeiting Trade Agreement, or ACTA, which is meant to clamp down on illegal commerce in copyrighted and trademarked goods. Opponents say that it will erode Internet freedom and stifle innovation. About 1.5 million people have signed a Web petition calling for the European Parliament to reject ACTA, which some say is merely SOPA and PIPA on an international level. Thousands of people have turned out for demonstrations across Europe, with more scheduled for next Saturday.

After more than three years of talks, which critics say were conducted without sufficient public input, the United States signed on to ACTA last October in Tokyo, along with Australia, Canada, Japan, Morocco, New Zealand and South Korea. (The agreement is to come into force when six of those countries have ratified it.)