All theories are provisional; they may be overturned or radically revised at any time by one more little experiment. Scientific "law" is no more than a theory that has withstood so many tests at so many times that even the canniest scientist wouldn't like to bet a brass farthing that they'll be alive on the day that a "law" is overturned. Yet such "laws" are overturned, or at least revised, often enough; Newtonian gravitation - your "Law of Gravity" from schooldays - won't deal with extremes of mass and velocity, so Relativity is necessary. The "Law of Causality" has received several excellent shocks in this last century. And this is all to the good, and the sloppy use of the term "Law" in the context of science is only that: a sloppy use - not an attempt to claim that a theory is Universal, Eternal and Unalterable.