  Systematic studies of the rotation rate of sunspot groups using white-light
images yield controversial results on the variations of the rotation rate:
sunspot groups were found to either accelerate or decelerate systematically.
This disagreement might be related to shortcomings of the method used to probe
the rotation rate of sunspot groups. In contrast to previous works, in this
study we use magnetic field maps to analyse the variations of the rotation rate
of active regions. We found that an active region may exhibit either
acceleration or deceleration during the emergence while the rotation rate
remains almost unchanged during decay. Hence, we suppose that there is no
systematic geometrical inclination to the radial direction of the apex of the
subsurface magnetic flux loop forming an active region. A thorough comparison
of the rotation rate of unipolar and bi/multipolar active regions revealed no
significant changes in the rotation rate of decaying active regions. In
contrast to previous works, we presume the rotation rate to keep constant
(within the expected uncertainties) during the evolution of an active region
after emergence.
