It seems that the police can turn up at any time and 'try' to breathalise a pilot.
About 15 years ago while in the crew hotel at Saarbrucken in Germany, the German Police arrived to breathalise the British crew flying a UK registered aircraft involved in an airmiss with an American fighter near Ramstein while under a German radar service in uncontrolled lower airspace near Ramstein. The local police arrived at the hotel about 2 hours after the airmiss incident. The crew involved were having a post flight drink in my room when the police arrived. Fortunately the police eventually agreed with us that a breath test would be pointless, and they left after taking statements.