Implies one is anxiously aware of possible threats, often because they've done something wrong. Ever since the scandal, the politician has been looking over his shoulder.
Pro Tip 2/3
Avoiding Trouble
Reflects the attempt to avoid being caught or facing consequences. After hacking into the system, she spent months looking over her shoulder.
Pro Tip 3/3
Stressful Caution
Indicates a prolonged state of stress due to fear of being pursued or harmed. He's been looking over his shoulder since he witnessed the crime.