As far as I can tell, you could translate that as "existing product". Given A and B, if A is already legally marketed, and B is basically the same thing, B has

As far as I can tell, you could translate that as "existing product". Given A and B, if A is already legally marketed, and B is basically the same thing, B has a lower bar to clear. Googling for "legally marketed predicate" turns up results like a 501(k) for a catheter[1] that the manufacturer says is "substantially equivalent" to another catheter already on the market. [1] http://www.accessdata.fda.gov/cdrh_docs/pdf/K963092.pdf http://www.accessdata.fda.gov/cdrh_docs/pdf/K963092.pdf