The Washington Post reports today that the Justice Department has ordered Arcelor Mittal (the world’s biggest steel company) to sell off its Sparrows Point mill in Baltimore “to preserve competition in the eastern U.S. tin mill market.”

Prior to the Arcelor-Mittal merger last year, three firms supplied most of the tin mill products (steel used for food, paint, and aerosol cans, etc.) consumed in the eastern United States: U.S. Steel, Mittal, and a Canadian subsidiary of Arcelor. Post-merger, only two firms supply most of the tin to that market and the Justice Department deems that to be a threat to competition.

Interestingly, just eight months ago, the U.S. International Trade Commission voted to continue antidumping restraints against tin mill products from Japan, citing a domestic industry that was vulnerable to a recurrence of injury from imports in the foreseeable future.

So, while the Justice Department forces companies to break up to promote competition, the ITC sanctions duties to quell it. If both agencies took long sabbaticals, I suspect the competition thing would resolve itself.