that's right, you can do that. but its informal (as you said) and it's usually used when the speaker wants to depreciate that person because he doesn't like him or his acting.

der + last name is also used in police reports, hence a formal setting. At work we often have patients who were brought by the police because they acted in a strange way or showed aggressive behaviour in public because of their mental illness. Then the police writes a report and we get a copy. And in those reports it's always written like "Der Mueller ....". Sounds quite strange to me but it seems to be standard.

It depends on the context... ----------------------------- 1. When referring to somebody for several times. "Sie warteten auf Björn, aber der war zuhause und schlief noch." They waited for Björn, but he was still at home, sleeping. "Peter, der zwei Jahre in London lebte, antwortete in perfektem Englisch". Peter, who lived in London for two years, answered in perfect english. --------------------------------------------------- 2. der + last name (when talking *about* someone) "Der Bierhoff wird nie was erreichen" *the* Bierhoff will never achieve anything. In this case, "der" is used to depreciate something called "Bierhoff" "Der Schröder hatte gute Ideen" *the* Schröder had good ideas. In this case, we use "der"...because...well...why not? It´s informal, and you wouldn´t say "der Schröder" when he is at hearing range...but it´s not depreciating. --------------------------------------------------- These rules apply to women aswell. You´ll have to use "die" instead of "der", though.

It's totally acceptable, but usually informal. I use it when I'm talking but I would avoid writing it in a formal text. Unless of course the sentence would otherwise be unclear. In your case it is about two men, so "der" refers to the one last mentioned so the reader doesn't confuse him and John, as both can be called "er".