It is not the laws of physics, but the forms of laws of physics which are the same in all inertial frames. Comment. "The forms of laws of physics are the same in all inertial frames" is a necessary condition (put by scientists ) to get satisfied by something which has to be called as a law of physics. To illustrate that it's not the laws of physics, but the forms of laws of physics which are the same in all inertial frames, let's consider Coulomb's electrostatic force law. Let's consider an inertial frame S in which two charged particles A and B with charges q and Q respectively are at rest and the distance measured between the two is r. Then, the force acting on Q is kQq / r2 ##\hat r## where ##\hat r ## is the unit vector along the line joining q and Q. W.r.t. another inertial frame S', the charges of the two particles remain same to that in S frame respectively. But, the distance between the two gets changed to r' (keeping special relativity) in mind.Then, the force acting on Q is kQq / r'2 ##\hat r'## where ##\hat r' ## is the unit vector along the line joining q and Q. So, it is observed that the Coulomb force between the two charged particles which is a law of physics is different for different inertial frames(due to special relativity), but the form of the force remains same in both inertial frames. The laws of physics differ only because of the special relativity,here. Under Galilean Transformation,both laws of physics and forms of laws of physics remain the same in all inertial frames. Is what I have written above correct? Galilean Transformations is valid only for inertial frames. Isn't it?