  Persistent scaling behavior of magnetization in layered high $T_c$
superconductors with short--range columnar defects is explained within the
Ginzburg Landau theory. In the weak field region, the scaling function differs
from that of a clean sample and both the critical and crossing temperatures are
renormalized due to defects. In the strong field region, defects are
effectively suppressed and scaling function, as well as critical and crossing
temperatures are the same as in a clean superconductor. This picture is
consistent with recent experimental results
