How to know my suppliers are not giving me pirate goods to sell?

I'm an importer and receiving a lot of samples from overseas suppliers. Some of them are very nice but I'm worried that the goods are violating someon else's copyrighted materials or patterned technologies/designs. What is the quickest way to verify that the goods are legal to be sold in the US? I need to check quite a lot of them since I try to carry as many products as possible.