(1) maintain an office for the practice of law in the United States;

(2) be a regular employee of an agency of government or of a business or other nongovernmental organization or association and be authorized to sign pleadings on behalf of the employer. The attorney shall not sign pleadings and papers on behalf of other clients unless both of the following requirements are met: (A) a substantial portion of the attorney's duties performed for the regular employer in the regular course of employment must constitute the practice of law, and (B) the office address as shown on the pleadings must be located in the United States and a substantial amount of the attorney's time must be spent in that office during ordinary business hours in the traditional work week; or

(3) have a practice limited exclusively to participation in a legal services or pro bono publico program sponsored or supported by a local Bar Association as defined by Rule 19-601 (b), the Maryland State Bar Association, an affiliated bar foundation, or the Maryland Legal Services Corporation, and the attorney shall include on the pleading or paper the address and telephone number of (A) the legal services or pro bono publico program in which the attorney is practicing, or (B) the attorney's primary residence, which shall be in the United States.

Cross reference: Rule 19-605.