Maryland Code, Courts and Judicial Proceedings § 10-705

(1) The defendant was served personally in the foreign state;

(2) The defendant voluntarily appeared in the proceedings, other than for the purpose of protecting property seized or threatened with seizure in the proceedings or of contesting the jurisdiction of the court over him;

(3) The defendant prior to the commencement of the proceedings had agreed to submit to the jurisdiction of the foreign court with respect to the subject matter involved;

(4) The defendant was domiciled in the foreign state when the proceedings were instituted, or, being a body corporate has its principal place of business, was incorporated, or had otherwise acquired corporate status, in the foreign state;

(5) The defendant had a business office in the foreign state and the proceedings in the foreign court involved a cause of action arising out of business done by the defendant through that office in the foreign state; or

(6) The defendant operated a motor vehicle or airplane in the foreign state and the proceedings involved a cause of action arising out of such operation.