Originally Posted by Doohickie

It doesn't matter. When executing a left turn across traffic, it is incumbent on the vehicle making the turn to ensure that ALL TRAFFIC LANES are clear before making the turn, because the people in their traffic lanes (including the bike lane) have the RIGHT OF WAY. You violate someone else's right of way, you're at fault. Period.

And just because a driver is ignorant of the presence of a bike lane does NOT excuse them of liability.

Put into a slightly different context, if, instead of a bike lane, that was an additional motor traffic lane, and all the other lanes had stopped due to traffic, but that lane was clear, the person in that last traffic lane wouldn't be at fault for a collision, the driver left turning across their lane would be. Same principle applies here.