The prime minister has said it is "very important... that the rules are followed" after becoming embroiled in a row about a donor paying for his wife's clothes.
Germany has started checks at borders with five more European countries in an effort to crack down on "irregular" migration and guard against Islamist threats.
The Criminal Bar Association has warned the government against increasing sentencing powers for magistrates, saying the "knee-jerk reaction" would "simply make things worse" for overcrowded prisons.