Do wizarding laws favor Wealthy Families and/or Pure Bloods?

The inspiration of this question comes from this comment by @JasonBaker: Why does Quidditch allow faster brooms?

Does the Harry Potter canon give evidence that wizarding laws favor Wealthy Families and/or Pure Bloods by any ways? I would like to see a part of answer dealing with the times when Voldemort influenced ministry, too. I am not sure whether Voldemort cared about wealth. He was racist with regards to blood status, but how did that affect the law?