Lawrence & Wishart has been losing the argument online, however. The publisher said that it had received about 500 irate emails, along the lines of “How can you say you are radicals?” There are more than 4,500 signatures on an online petition to oppose the notion of a copyright claim on Marx’s and Engels’s writings; the petition cites the incongruity, noting that the two philosophers “wrote against the monopoly of capitalism and its origin, private property, all their lives.” And the libertarian Cato Institute enjoyed teasing its ideological adversaries with an I-told-you-so blog post titled, “Because Property Rights Are Important.”

Ms. Davison said she was flabbergasted to see Lawrence & Wishart cast as the oppressor. The publisher has two full-time employees and two part-time employees and barely makes ends meet, publishing a handful of journals, like Anarchy Studies, and about a dozen left-wing books a year, she said.

“We make no profit and are not particularly well paid,” she said.

Ms. Davison defended her position by quoting Marx to the effect that you must adapt to real-world conditions: “We don’t live in a world of everybody sharing everything. As Marx said, and I may be paraphrasing, ‘We make our own history, but not in the conditions of our own choosing.’ ”

The publisher also tried to turn the tables on its critics, questioning whether it was indeed radical to believe that there is no ownership of content produced through hard work, like the mammoth translation and annotation of Marx’s and Engels’s work, a project initially directed by the Soviet Union in the late 1960s that took some 30 years of collaboration among scholars across the world.

In a note on its site, Lawrence & Wishart said its critics were not carrying on the socialist and communist traditions, but reflecting a “consumer culture which expects cultural content to be delivered free to consumers, leaving cultural workers such as publishers, editors and writers unpaid, while the large publishing and other media conglomerates and aggregators continue to enrich themselves through advertising and data-mining revenues.”

Image Karl Marx Credit... Henry Guttmann/Getty Images

The statement noted that many works by Marx and Engels — including “The Communist Manifesto,” which urges, “Workers of the world, unite!” — were freely available in translation on the nonprofit archive and other sites.