freakparade3 wrote:I can't find any specific information but it may have something to do with master using the KW1 keyway for their deadbolt and knob locks.
If it was about keyways it would be the other way around (Master suing Kwikset).
A little bit of history about residential locks: The keyway that kwikset has was originally designed by Dexter and it was meant to have a key that would fit all of the common locks that were around at the time (weiser, weslock, some falcons and a few more) so people could buy a brand new dexter lock and have all their existing locks keyed to their new dexter key. Kind of a combination of marketing and convenience. Kwikset then came out and copied their idea.
Master actually bought out Dexter (or they might have just merged), and continued to market them as Dexter for a time then started stamping master on all of them. Anyways none of that matters because nobody patented their keys until they started making highsecurity locks like medeco, schlage everest, then schlage primus and so on.