Definition of retroactive law
: a law that operates to make criminal or punishable or in any way expressly affects an act done prior to the passing of the law — compare ex post facto law
Start your free trial today and get unlimited access to America's largest dictionary, with:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Seen and Heard
What made you want to look up retroactive law? Please tell us where you read or heard it (including the quote, if possible).