If you want to get out of jury duty, just tell the truth. When asked if you can put aside your bias against a potential kind of witness, tell them you don't know. It worked for me. The irony was that I wanted to serve on that jury. It wasn't a two-month murder trial. It was three days for assault with a deadly weapon. I have a law degree, but I had never seen a real trial and thought it would be an interesting experience.
This was not a jury pool of the unemployed and the elderly. But while there were plenty of my peers, I didn't notice any who might be presumed to be the defendant's peer once you got beyond breathing. I listened, fascinated, while the lawyers asked my fellow candidates if they could ignore the nasty personal run-ins they said they'd had with criminals or the police and reach a verdict based solely on the evidence presented and the law. All said yes, they could. Sure, they could. When the lawyers made their challenges, I fully expected a handful of these paper saints would spend the rest of the week mowing their lawns.
When it was my turn, I didn't say I couldn't ignore my confessed bias against a certain type of witness or two -- just that it would depend on what they said.
I think it's a silly question -- what the morality trade calls a "wallet question": as in, what would you do if you saw a wallet lying in the street? It's asking people to predict their reaction to the unknown. But my answer was even sillier. The jury system has no room for philosophers. It wants people who can swear it will rain tomorrow. Of the 12 voir-dired, they dismissed only me. That I told the truth was irrelevant. Prejudice inevitably lurks behind our decisions, but if I truly wanted to serve, I should have answered like the rest. In practicing my uncertainty principle, I had been far too scrupulous. We don't shoot weathermen for getting the weather wrong.
The jury system is an imperfect institution in which imperfect people pass judgment on other imperfect people. If everyone gave the answer I did, it would grind to a halt.