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A Look at Montgomery County’s Proposed Restrictions on Pesticide Use: What Exactly is Preemption?

Updated: Jul 8, 2020

Solar panels on a farm (Photo by Edwin Remsberg).

This post should not be construed as legal advice.

Many local governments may see holes in Federal and state laws and decide to implement local ordinances to fix these holes. But although local governments may have the best intentions when implementing such ordinances, these ordinances may not be valid due to something known as preemption.

One such example is currently being debated in a Maryland county. In October 2014, Montgomery County proposed a county ordinance which could potentially require posting of certain lawn applications of pesticides, prohibit the use of certain pesticides on lawns and county-owned property, and require the county to adopt integrated pest management (IPM) on certain county-owned property (Bill 52-14). The proposed ordinance currently includes exceptions for agriculture, gardens, and golf courses, but I have been asked whether Montgomery County has the authority to regulate the use of pesticides. So will the proposed ordinance be preempted by state or Federal law?

Tractor on a field (Photo by Edwin Remsberg).

One note before we start. In Wisconsin Public Intervenor, the U.S. Supreme Court ruled that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), a Federal law which set up the basic framework for the regulation of pesticides in the United States, did not preempt local governments (like a county or a city) from passing certain types of local regulation for the use of pesticides. While this may be the case, other preemption principles, as we will discuss, can limit or prevent local governments from regulating the use of pesticides.

Although, the proposed Montgomery county ordinance may not be preempted by federal law the proposed ordinance maybe preempted under state law. Maryland’s Pesticide Applicator’s Law gives the Secretary of Agriculture the authority to adopt regulations related to the use of pesticides in the state. The law also gives the Secretary the authority to establish the guidelines for applications. Montgomery County’s proposed ordinance may still have preemption issues with state law.

What is Preemption?

Preemption occurs when a state statute is in conflict with a local ordinance on the same subject. In those cases, the state statute will preempt the local ordinance. There are various types of preemption; a state statute can expressly prohibit local governments from regulating in a particular area. This type of preemption is known as express preemption. For example, some state statutes will contain language that “any local ordinance, regulation, or laws are void and have no effect.” This would be an example of express preemption.

Plane over a field (Photo by Edwin Remsberg).

Another form of preemption is implied preemption, which occurs when state laws give the impression that the intent of the state was to occupy the field and exclude local ordinances. For example, the Court of Appeals of Maryland has found that a county ordinance requiring the filing of certain information before applying sewer sludge was preempted by a comprehensive state law scheme (Skipper, 1993).

The third type of preemption is preemption by conflict. This occurs when a local ordinance prohibits an activity intended to be permitted under state law. Preemption by conflict can also occur when the local ordinance allows an activity prohibited by state law. For example, Worcester County could not limit the amount of allowable nitrogen in wastewater applied to a property (Hadder, 1996).

Would the Montgomery County Ordinance Be Preempted?

Just to be upfront, I have no idea how to answer this question, but I’m sure if passed a court will eventually let us know on the preemption question. As the Court of Appeals has pointed out a few times, there is no particular formula in determining if the General Assembly has intended to preempt an entire field. Let’s look at a couple of examples from previous cases where a Maryland court found a county ordinance preempted by state law.

In Skipper, Talbot County passed an ordinance requiring landowners to record certain information in the county land records before applying sewer sludge in accordance with a state permit. The Court of Appeals found that the Maryland General Assembly had acted to occupy this entire area of law, leaving no room for Talbot County to regulate.

In Holiday Pointe Marina Partners, the Court of Appeals found that state law did not preempt a zoning ordinance related to the siting of marina facilities along bodies of waters in Anne Arundel County. In that case, the Court did not believe that state regulations related to tidal wetlands, water quality, and shellfish so the county zoning ordinance regarding siting of a pier was rightfully passed.

Lambs in the grass (Photo by Edwin Remsberg).

Recently, a county in Hawaii implemented regulations requiring disclosure when certain pesticides were used, use of buffer zones when pesticides are used, and required the county to undertake an environmental review of the use of pesticides (County of Kauai, 2014). This ordinance was challenged in Federal court, and the Court found the ordinance to be preempted by state law. In looking at Hawaii’s pesticide law, the court found that counties were absent from rulemaking, enforcement, and oversight of pesticides. This would be an example of preemption by conflict.

Similarly, Maryland’s law makes no reference to counties being involved in the rulemaking, enforcement, and oversight of pesticides in Maryland (Md. Code. Ann., Agric. §§ 5-101 to 5-211). Maryland’s pesticides laws, like many states’ pesticide laws, give the Secretary of Agriculture the power to determine rules and regulations in the application of pesticides. One interesting note, the Maryland Pesticide Applicator’s Law gives the Secretary of Ag the power to “establish guidelines and requirements for the application of pesticides and providing for submission of records to the Secretary” (§ 5-204(5)). This seems similar to what Montgomery County is attempting to do in the proposed ordinance. Montgomery County’s proposed ordinance may face a similar fate as Kauai County’s if passed, but a court will be the ultimate decider in that situation.


Holiday Pointe Marina Partners v. Anne Arundel County, 707 A.2d 190 (Md. 1998).

Md. Code. Ann., Agric. §§ 5-101 to 5-211 (West. 2015).

Perdue Farms, Inc. v. Hadder, 675 A.2d 577 (Md. Ct. Spec. App. 1996).

Syngenta Seeds, Inc. v. County of Kauai, Civ. No. 12-000014 BMK, 2014 WL 4216022 (D. Haw. Aug. 25, 2014).

Talbot County v. Skipper, 620 A.2d 880 (Md. 1993).

Wisconsin Public Intervenor v. Mortier, 501 U.S. 597 (1991).

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