Wanting to work on issues with more impact than “just solving rich people’s problems,” Marcia Ludkin left her in-house counsel role in the fine arts business at Christie’s International and went on to become general counsel of the third largest labor union in the United Kingdom.

Ludkin worked at Christie’s in London and New York for nearly eight years, leaving in 2000 to pursue a private practice in San Francisco, according to her LinkedIn profile. In 2006, she returned to London as general counsel of GMB, formerly General, Municipal, Boilermakers and Allied Trade Union.

In an interview with attorney and columnist Reuben Guttman, who heads Grant & Eisenhofer’s Washington, D.C., office, she said that while she “loved working with the extraordinary colleagues in the art world,” she also wanted to work on issues with a bigger impact than “just solving rich peoples’ problems.” Guttman’s article appeared this week in the Global Legal Post.

“The working poor need good lawyers,” too, she told Guttman.

So in 2007, she and her union were part of an effort to take on private equity investors who break what she called implicit contracts with the workforce. Skillfully taking her campaign to the press, she argued that low-income people who cleaned offices were paying more taxes than the private equity partners whose offices were being cleaned, according to the article.

Guttman said her tactics won her “the moral high ground, and successfully brought about changes in regulations of private equity firms” in England.

Now Ludkin is taking on the giant e-commerce company Amazon.com Inc. on behalf of 20,000 U.K. warehouse workers. She claims the warehouses in England are so large that workers must record at least 15 miles on their feet a day or face termination.

To gain popular support, “We had to create a visual image of these contract employees who work 10.5 hour shifts walking over 15 miles a day,” she explained to Guttman.

Neither Seattle-based Amazon nor its general counsel, David Zapolsky, returned messages seeking comment.

But the British legal press recently reported that the company is hiring more in-house lawyers in Europe, luring attorneys from London’s Allen & Overy and Eversheds, as well as an in-house counsel from money transfer company Moneygram International Inc. The company’s U.K. in-house team is led by legal director Robert Mackenzie.