Well the "laws" are only abstractions of the data we've collected by observation. They very well may be, and in some cases have turned out to be, mostly true or simplifications. The more we know about physics, the more we learn there are no hard and fast laws, and we also learn that we should be cautious about putting a "period" at the end of a statement of physics "truth".
In the late 1800s, we really thought we were almost at a complete understanding of the universe - there were just a few pesky unexplained phenomena that we would certainly figure out soon, the photoelectric effect (that led to quantum mechanics and its weirdness, and the death of classical physics with its pure, non-probabilistic determinism) and the fact that the speed of light seemed to need to be represented as a constant, despite Newtonian mechanics suggesting that it, like any other velocity, must be subject to revision when faced with motion relative to light. Einstein and other physicists demonstrated light has wave and particle like aspects, depending on the measurement, and that the speed of light is constant regardless of one's state of motion, which means time "flows" at a slower rate and lengths contract for the faster moving object, when compared to an observer closer to rest with respect to that observer. And, as weird as it all seems, it turned out both of these predictions can be repeatedly experimentally verified. The universe is weird, and evolution did not prepare us for how much.
As we learn more, the "laws" will change. We don't even know if the laws are constant or in flux - we never can know, since we always have to go under the assumption that there is an underlying constant order that can be expressed as a theory that doesn't change, and we'll take all the crazy observations and experimental evidence and try to come up with an even crazier theory that makes it all come together in the most elegant way possible. Even armed with a so-called "theory of everything", we may find, even if it takes a million years of this theory being perfectly accurate at high levels of precision at explaining and predicting all observed phenomena, that someday something is observed that throws the whole theory into question. More frustratingly, we may find competing theories that are equally elegant and equally successful, and there may ultimately be no way to resolve this embarassment of riches. We're not there yet though. We may yet find new laws of physics - one idea gaining ground is a law of "scale relativity", that the laws of physics are not only the same for any observer regardless of state of motion, but also regardless of scale / size.
Some people mean, by "laws" of physics, the constants. Well, there is a lot of evidence that some of the constants, such as the speed of light, may fluctuate over long periods of time. The fine structure constant, alpha, which depends on the speed of light, has changed by a small amount over the course of the history of the universe. Although it deeply complicates our theories, some physicists have responded by representing one or more of the so-called fundamental constants in their equations as vector-fields, so that theories allow for them to change over time while retaining their structure and accuracy. It is unclear how much of the constants are really variable but barely noticeable as being variable because the variability is so small, how many are really constant, if any, and how we might explain and represent such variability. My gut instinct is that we'll find that every constant turns out to be only a close approximation of a variable vector-field.
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