What laws did Mr.Powers discover the railroad company was violating?

From the text:

He turned over a page mechanically, not meaning to read what was not addressed to him, but, before he knew it, he was in possession of evidence which conclusively proved that the company was engaged in a systematic violation of the Interstate Commerce Laws of the United States. It was as distinct and unequivocal a breaking of law as if a private citizen should enter a house and rob the inmates. The discrimination shown in rebates was in total contempt of all the statute. Under the laws of the state it was also a distinct violation of certain provisions recently passed by the legislature to prevent railroad trusts. There was no question that he had in his hands evidence sufficient to convict the company of willful, intelligent violation of the law of the Commission and the law of the State also.