If Person A starts shooting at me, and grabs Person B to use as a human shield...
... and of necessity I shoot back in defense of my life...
... and as a result both Person A (the shooter and shield-grabber) and Person B (the unfortunate shield) are both killed, it is Person A's fault.
Person A initiated the conflict by trying to shoot me. Person A put Person B's life in danger by grabbing him and using him as a human shield. I did what was necessary to preserve myself; I am not responsible for PersonB's death, person A is responsible, he is the one who put B in the line of fire while forcing me to respond.
Perhaps I could have ducked behind cover and just let Person A go.
... perhaps instead of leaving, he would have approached my cover and tried to finish me off at close range, still using his human shield.
... perhaps I am an LEO tasked with apprehending this person; perhaps he is a known murderer, and if I let him escape with Person B then he is likely to murder him anyway.
Perhaps I could have done something else...
... like what? Rush to HTH range in the open and under fire? Bit suicidal...
... try for a head shot? Sure, if possible... but pinpoint precision is always difficult under such conditions.
Intrestingly enough, as an LEO, I went thru some training on how to deal with being a hostage. We were told the following:
... 1. You (the officer) are expendable; we will not release a prisoner or allow a felon to escape to save you.
... 2. When SWAT rolls in, hit the floor, because the killing is about to start; they will try not to shoot you, but if you're in the line of fire you may be shot anyway.
I was transporting a group of 14 post-conviction felons from one place to another, once. At the destination facility, I took them into a secure room to remove their restraints. Before doing so I locked my sidearm outside the room to prevent their possible access to it (SOP). Normally I would have (should have) had some help, but we were short-handed, so I removed all their restraints myself, prior to their induction into the facility.
Before anyone else could arrive, one convict and his buddies threatened to take me hostage and kill me if they were not released. I explained to them Fact 1 and Fact 2 listed above, and they were deterred and surrendered without further action. (well, I also had a fistful of chains and told them I would definitely kill at least one of them first, but...lol)
If my department allowed prisoners to get away using officers as human shields, such incidents would probably be more commonplace.