A witness takes the stand, and answers a number of questions about the issue in controversy. Then the opposing side gets to "cross" examine him or her.
To what extent is cross examination limited only to subjects brought up in direct examination? Can the cross examiner dig into a bunch of background issues in a witness' past to prove bad character or bias, for instance? Or is there an "intermediate" position whereby cross examination is limited to issues brought up on direct examination, plus certain specific "tangential" issues not brought up previously (e.g. "rape shield laws protect a victim from being asked certain questions).