Do you have the car seat in the middle or on the sides of the car?

I’m just curious because a friend of mine recently paid to have her car seat professionally installed and it was installed in the back seat on the passenger side. I have my car seat in the middle because both my mum and mother in law always did with the mentality that if the car is T-Boned baby won’t cop direct impact...

So where do you have your baby seat (obviously this doesn’t apply to cars with multiple baby car seats, but where did you put your first child’s car seat?) and why, and is there any legislation saying where is should technically go?