Answer:
Worried about a possible antitrust lawsuit, the company’s leaders met privately with Roosevelt. They offered to open their files for examination. In exchange, the Department of Commerce and Labor would privately tell the company about any problems and allow them to fix the problems quietly. Roosevelt accepted this “gentlemen’s agreement,” as he called it, and soon made similar deals with other companies. These deals gave him the ability to regulate big business without having to sacrifice economic efficiency by breaking up the trusts.
A copy and paste from my history textbook. While he did take one group to court he found that it hurt the economy and scared business owners.