Maryland Code, Real Property § 12-105.1

(a) Notwithstanding any other provision of law, the State or any of its instrumentalities or political subdivisions shall file an action to acquire private property for public use by condemnation within 4 years of the date of the specific administrative or legislative authorization to acquire the property.

(b) If an action for condemnation is not filed within 4 years of the date described in subsection (a) of this section, the State or any of its instrumentalities or political subdivisions may not proceed with condemnation until it first obtains a new authorization to acquire the property.