After the fact
Definition 1 of 1
Pro Tip 1/3Retroactive Context
Used when discussing actions taken or events happening after the main event or situation. 
We installed the security system after the fact, which we regretted not doing sooner.
Pro Tip 2/3No Prevention
Emphasizes that it's not about preventing, but responding to something that has already happened. 
The apology came after the fact, failing to prevent the upset.
Pro Tip 3/3Hindsight Insight
Implies learning or realizing something afterwards, often with a sense of missed opportunity. 
She recognized the signs of the illness only after the fact.