Effective Dates for Maryland Legislation
When does new legislation take effect in Maryland? Article III, Section 31 of the Maryland Constitution provides that, "A Law passed by the General Assembly shall take effect the first day of June next after the session at which it may be passed, unless it be otherwise expressly declared therein or provided for in this Constitution." Article XVI, Section 2 says that, “No law enacted by the General Assembly shall take effect until the first day of June next after the session at which it may be passed.”
In practice the legislature uses June 1 as the effective date for bond bills, July 1 as the effective date for budget, tax and revenue bills and October 1 as the date for most other legislation. A key exception is “Emergency” legislation, which is effective on enactment, under Article XVI, Section 2.
There is a special rule for laws passed without the governor's signature. Article II, section 17(d) of the Maryland Constitution says that, "Any Bill enacted over the veto of the Governor, or any Bill which shall become law as the result of the failure of the Governor to act within the time specified, shall take effect 30 days after the Governor's veto is over-ridden, or on the date specified in the Bill, whichever is later." (Again, there is an exception for "Emergency" legislation, which takes effect on the date of the override.) The Maryland General Assembly website posts an updated list of 2006 Veto Overrides.
For more on the effective dates of Maryland legislation see Section X(17) of the Legislative Drafting Manual posted by the Department of Legislative Services.