How did state law overrule federal law during life under the Articles of Confederation?

I know that each state had a vote, and in order to create a law there must be either 9/13 votes for or a unanimous decision, I cant remember right now.

But the idea that my teacher was trying to get across to me was that state law at times overruled federal law, and it is what citizens were mostly concerned with.

Any examples anyone could give would be fantastic. Thanks!