Maryland Code, Estates and Trusts § 5-102

(a) Unless it is admitted to administrative or judicial probate, or recorded as provided in § 5-504 of this title, a will is ineffective to transfer property or to nominate a personal representative.

(b) Except for a foreign personal representative, a person may not qualify as or exercise the powers and duties of a personal representative unless the person has been appointed administratively or judicially.