Re: Sheltering Criminals.
"They are not there to circumvent the judicial system of their host country."
It is if it is in the interests of diplomatic relations. It's part of the give-and-take. If the host country decides to just barge in, then the guest's safety (diplomatic or otherwise) cannot be guaranteed, meaning the most likely course is to sever relations, meaning there is no more communication between the countries. Basically, if an embassy cannot protect its own citizens, it cannot protect the diplomats, either: part and parcel.