Maryland Real Property Section 13-401
§ 13-401.
  The following persons may file an objection to the granting of a patent for all or any portion of the land described in the application:
    (1)   Any person or governmental body with prior title to any portion of the land, except that, if the land is land for which a patent never has been issued, the State and its agencies may object only in accordance with item (3) of this section;
    (2)   Any person who possesses any portion of the land under claim of ownership in a manner that, either directly or by tacking, is actual, open, notorious, exclusive, and continuous and uninterrupted for the 20 years immediately preceding the date of filing the application; and
    (3)   The State or any agency of the State that requires any portion of the land for public purposes.