The Difference Between "Based On a True Story" & "Inspired By a True Story" in Film & TV Credits

You may have noticed, some film's title cards state "Based on a True Story" while others read "Inspired by a True Story". So, what's the difference?

The “rule of thumb” to determine if a script is “based on a true story” vs “inspired by a true story" is: 

“Based on a true story” means much of the actual story and events remain intact in the script. The writer may make significant adaptations (creating composite characters, truncating or shifting the timeline, changing names, locations, ages, gender, etc.) but the core of the story remains the same. There is source material for the writer to refer to when crafting the script, such as books, articles, films, media files, and/or people. Example: The King’s Speech.

American Hustle is considered “based on a true story”, even though the ending is entirely fictionalized for dramatic effect (to provide a satisfactory conclusion for the audience).

Braveheart is considered “based on a true story”, even though, among other discrepancies from fact, William Wallace could not have had an affair with Isabelle of France (who was only 4 or 5 years old in the specific time period).

“Inspired by a true story” means a real person or event (or events) only triggered the idea for the script, but does not follow the trajectory of the true story. Often the material takes a “what if” approach to explore the issues. Example: many Law and Order television episodes. 

Another example would be a script written about the real historical person Ann Boleyn that tells a story of her living happily ever after with King Henry VIII instead of being put to death.