  Two recent works suggest a possibility of sending signals to a space-like
separated region, contrary to the spirit of special relativity. In the first
work [J. Grunhaus, S. Popescu, and D. Rohrlich, Phys. Rev. A 53, 3781 (1996)]
it has been shown that sending signals to particular union of space-like
separated region cannot cause causality paradoxes. Another work [Y. Aharonov
and L. Vaidman, Phys. Rev. A 61, 052108 (2000)] showed that the relative phase
of quantum superposition of a particle in two separate locations can be
measured locally. Together with the possibility of changing the relative phase
in a nonlocal way using potential effect we, apparently, have a method of
sending signals to space-like separated regions. These arguments are critically
analyzed in this paper.
