I had an attempted murder case last year where our material witness was in Placer County Jail on an unrelated charge and we needed her for our case. I found out that she had two outstanding felony warrants in our home jurisdiction - nothing reallys serious (receiving stolen property) but enough I believed to "warrant" extradition. In my own experience as a former police officer, I'd seen the state authorize this action in the name of justice (i.e. to prosecute the offender with the warrant).
I should have known better. Justice isn't really factor when bringing a low level offender to justice also assists in the defense of a person accused of something more serious. The judge immediately complained about the cost of this project and directed me to find out if the public defender's office would absorb the cost for travel (lodging, at least for the witness wasn't a problem - she would have had a bed waiting for her at the "county country club").
I took the stand and the prosecutor wanted to know exactly what the witness had told me about the case. I told him I had no idea becasue I didn't ask and didn't read the file. The judge was incredulous. "You didn't read the file? You didn't interview the witness?" he asked.
Of course I didn't. I'm not about to take the chance our witness may decide to say something different.
In the end we never got the witness back and the client took a plea. The whole episode was an exercise in cost-benefit analysis.
Sort of reminds me of the lyrics from Dylan's Hurricane:
"Couldn't help but make me feel ashamed to live in a land where justice is a game."