As many other commenters pointed out, this is completely misinformed -- he didn't break any laws. He also makes for an interesting case study on monopolies, because he did not actually attain as much rent-seeking as many people think, or even compared to today's companies. Natural, malevolent monopolies cannot exist without rent-seeking, and Rockefeller was a great example of that. His empire was very close to a monopoly, but it was not malevolent to the consumer -- he had driven down the price of kerosene by over 50% after 30 years.