In this article, Andrew Grace of KPMG LLP, discusses a recent Maryland Court of Special Appeals decision in which the court upheld the Comptroller's assertion of nexus over two out-of-state subsidiaries using the unitary business principle. Mr. Grace contends that the court incorrectly blurred the lines between separate state tax doctrines when, based on the in-state presence of the subsidiaries' parent, the court looked to the unitary business relationship of the parent and the subsidiaries as a justification for asserting nexus.