Is Einstein's Special Relativity completely inclusive of Newton's 3 laws of motion? Relativity has always been explained to me (in books I've read, etc) as a superset of newton's laws - that is; it encapsulates all of Newton's mechanics in addition to other effects (observer effect, time dilation, space-time geometry, etc). 
I can kind of imagine 2 of Newton's 3 laws of motion to be incapsulated within Einstein's Special Relativity, but the one about "for every action there is an equal and opposite reaction", I'm struggling to find a place for that within Special Relativity. 
Does this sit outside Special Relativity's explanatory power or is it inferred within somehow? 
 A: Newton's third law is really a special case of the conservation of momentum. Suppose you have two rigid bodies with momenta $\mathbf{p}_1$ and $\mathbf{p}_2$. If they only interact with each other, then $\mathbf{p}_1 + \mathbf{p}_2$ is constant, since total momentum is conserved. Differentiating this gives $\frac{d\mathbf{p}_1}{dt} + \frac{d\mathbf{p}_2}{dt} = 0$. But this is just $\mathbf{F}_{21} + \mathbf{F}_{12}$ (i.e., the external force exerted on body 1 plus the external force exerted on body 2).
In relativity we usually don't use the concept of force, preferring to deal with momentum instead. Momentum is conserved in relativity, just like it is in Newtonian mechanics.
A: Newton's first law (really Galileo's law of inertia):
This works as well in Special Relativity as it does for Newton.  If an object has a constant relative speed near the speed of light and no force acts on it, it keeps moving at a constant relative speed.  Check.   Can't go faster than light, though.
Newton's second law:  F=ma
Acceleration depends on time, and time is relative to the state of motion of the observer.  For someone doing physics in an inertial reference frame, of course F=ma still works like it always did, at low speeds at least.   Trying to push something from rest to relativistic speeds is a whole different story.  It appears to get more massive (and harder to accelerate).  And the speed of light is still the top speed limit.
Newton's third law: Action - Reaction (force pairs)
Works until you are applying force to something already moving near the speed of light.  Energy still gets pumped in, but it doesn't move much faster, and can't exceed the speed of light under any circumstances.
