Basically just the trolley problem, but the tracks are already aligned to killing fewer people. There is a vote on whether to divert the trolley to the track which would kill more people or stay the course. Is there blood on your hands if you abstained and convinced others to abstain which resulted in a win for changing tracks?

Let not any one pacify his conscience by the delusion that he can do no harm if he takes no part, and forms no opinion. Bad men need nothing more to compass their ends, than that good men should look on and do nothing. He is not a good man who, without a protest, allows wrong to be committed in his name, and with the means which he helps to supply, because he will not trouble himself to use his mind on the subject.

-- John Stuart Mill