The US agents are saying that Gibson violated the Lacey Act:
"The law ensnaring Gibson is the Lacey Act of 1900, originally passed to regulate trade in bird feathers used for hats and amended in 2008 to cover wood and other plant products. It requires companies to make detailed disclosures about wood imports and bars the purchase of goods exported in violation of a foreign country's laws."
From another article that I read a week or two ago, Gibson had two problems: one was some ebony that was incorrectly labled, and the other, IIRC, was related to some East Indian Rosewood that was illegally exported. The issue with the EIR had something to do with an Indian law that says something to the effect of: if the piece is more than 1/8" thick, it must be processed using Indian labor. I assume the search recovered some thicker stock.
It seems minor, but I believe these are the two issues that required a raid with armed agents and multiple plant closures...