It is not mandatory everywhere but yes some hospitals will not let you take the baby home unless you have the certificate of proper installation. IMHO and on the advice of an accredited installer I would always get it prpfessionally fitted for rear facing mode because the seats and capsules have to sit at a certain angle and they hav the correct inclinometer equipment to measure it is at the right angle and they may have toi pack the seat up or out to get the correct fit etc etc. The installer then showed us how to do it ourselves properly when we turn the seat later on....he said it is more staright forward to install a seat forward facing but rear facing should always be professionally done.