  A convenient framework for dealing with hadron structure and hadronic physics
in the few-GeV energy range is relativistic quantum mechanics. Unlike
relativistic quantum field theory, one deals with a fixed, or at least
restricted number of degrees of freedom while maintaining relativistic
invariance. For systems of interacting particles this is achieved by means of
the, so called, "Bakamjian-Thomas construction", which is a systematic
procedure for implementing interaction terms in the generators of the Poincare
group such that their algebra is preserved. Doing relativistic quantum
mechanics in this way one, however, faces a problem connected with the physical
requirement of cluster separability as soon as one has more than two
interacting particles. Cluster separability, or sometimes also termed
"macroscopic causality", is the property that if a system is subdivided into
subsystems which are then separated by a sufficiently large spacelike distance,
these subsystems should behave independently. In the present contribution we
discuss the problem of cluster separability and sketch the procedure to resolve
it.
