  The problem of giving a (CR-)geometric description of the best possible order
of a subelliptic estimate at a boundary point in the $\bar\partial$-Neumann
problem is largely open. In this paper, we introduce a novel technique based on
a "$\bar\partial$-uncertainty principle" and, as an application, we determine
the sharp order of subellipticity at the origin for a large class of Kohn's
special domains in ambient dimension $\leq 5$.
