Oh what good news!
"legal ownership" depends upon the country/city/county you live in.
Some cities/counties in the USA say, if you feed the cat, you own the cat, so you are responsible for care, etc., including potential law suits if the cat bit a neighbor.
Some cities/counties have taken a more enlightened approach and either don't say one way or the other or say, you're not legal responsible.
In some jurisdictions, it is illegal to let an unfixed cat roam outside--but...