"I'm still shaking. So I say that she was raped and murdered by a serial rapist and the case was brought back out due to DNA evidence. The judge then asks if I could be impartial if this lawyer were to be involved in our case and I said no, I could not, honestly. He then asks if I have any medical conditions and if I'm on medications for them. "Yes, I'm bipolar," I answer. "Did you take your medication today?" he inquires. "Yes," I reply. The lawyers and the judge have one of their little meetings for a minute or two and then tell me that my duty is over and I may leave."

You were dismissed because you admitted you couldn't be impartial, under circumstances that made your statement believable. Sometimes people will say that can't be impartial just to get out of jury duty, but you probably weren't sending those signals.

Being bipolar and on meds alone wouldn't be enough to excuse you, unless your symptoms weren't being controlled. The judge may have asked you these questions to verify the cause of your emotional reaction.

When picking jurors, judges and lawyers try to eliminate not only those with biases, but also anyone who, for whatever reason, may not be able to pay attention to the evidence presented in the case.

Curiously, it's normal for jurors, even those who want to get out of service, to feel a bit let down when they're dismissed -- "Why wasn't I good enough to be a juror?" That may be part of why you're asking the question now. :-)

Btw, I'm a lawyer with years of experience in picking juries in civil (no criminal) cases. I'm not able to do jury trials any more because of worsening bipolar disorder.