If the portion of code that Copilot lifts is the "heart" of the original work, that would be much less likely to be considered fair use[1], regardless of the length.

> For example, it would probably not be a fair use to copy the opening guitar riff and the words “I can’t get no satisfaction” from the song “Satisfaction.”

I wonder how this could be integrated into the system?

[1] https://fairuse.stanford.edu/overview/fair-use/four-factors/...