Okay kiddo, so you know how sometimes people get in trouble with the law and have to go to court? Well, sometimes when they go to court, they might say that what they did wasn't really their fault because it was impossible for them to do anything differently.
So, let's say someone was accused of stealing a piece of candy from the store, but they were actually at home sleeping when the candy was stolen. They could use the impossibility defense and say, "it was impossible for me to steal the candy because I wasn't even at the store at that time."
Basically, the impossibility defense is when someone argues that they couldn't have done something wrong because there were circumstances that made it impossible for them to have done anything differently. It's like they're saying, "I didn't do it because I couldn't have done it even if I tried."
Now, just because someone uses the impossibility defense doesn't mean they'll automatically be let off the hook. It's up to the judge and jury to decide if their argument is true and if they should be found guilty or not guilty.