Recent lattice calculations have demonstrated that the QCD static potential for sources in different representations of the gauge group is proportional to the eigenvalue of the corresponding quadratic Casimir operator with an accuracy of a few percent. We discuss the present theoretical status of this "Casimir scaling" phenomenon and stress its importance for the analysis of nonperturbative QCD vacuum models and other field theories. It is argued that Casimir scaling strongly advocates the property of Gaussian dominance of nonperturbative QCD vacuum. We also briefly discuss possible future tests to improve our understanding of the phenomenon.
