Hi!
You can absolutely go with something outside corporate or commercial law! For this type of question, the key isn't necessarily to pick a "law-related" event (and it can usually work to your advantage to pick something outside of law) - I would aim to show thoughtfulness and reflection in your answer. A historical, scientific, or cultural moment can work just as well, particularly if you tie it back to why it matters to you personally or why you find it interesting.
Even if you don't choose a commercial event, you can still make a subtle connection to law (or values you admire in legal work) without it feeling forced. For example, you could potentially choose a landmark civil rights case or a famous trial that you found interesting. You can even go fully outside law but highlight certain skills or traits that would be beneficial in law - e.g. analytical thinking, ethics, problem-solving, etc.
I would say that the main thing to avoid is a cliche "big corporate deal" answer unless you have a genuinely unique angle or a past experience that demonstrates why it particularly resonated with you - your idea of linking it to law but not commercial law sounds like it can work well!
Ultimately, I would answer the question truthfully, even if this is outside of law. This is likely to be the most genuine and reflective answer, and will read a lot better than trying to force an overly commercial angle