On June 3, 2025, the Mayor & City Council of Baltimore, the <a href="https://climatecasechart.com/case/city-of-annapolis-v-bp-plc/">City of Annapolis</a>, and <a href="https://climatecasechart.com/case/anne-arundel-county-v-bp-plc/">Anne Arundel County</a> (the municipalities) filed their opening brief in the Maryland Supreme Court in their appeals of trial court decisions dismissing their climate change cases against fossil fuel industry defendants. The municipalities initially appealed to the Appellate Court; the defendants then filed a petition for writ of certiorari in the Maryland Supreme Court; and the Supreme Court issued a writ of certiorari on April 24, 2025, limited to seven questions, the first of which asked whether the U.S. Constitution and federal law preempted “state law claims seeking redress for injuries allegedly caused by the effects of out-of-state and international greenhouse gas emissions on global climate.” The other six questions related to whether Maryland law precluded nuisance, failure-to-warn, and trespass claims in the context of products produced, promoted, sold, and used around the world and whether the municipalities stated claims for public and private nuisance, strict liability and negligent failure to warn, and trespass. The municipalities argued that their claims were not preempted by federal common law or the Clean Air Act, or barred by any constitutional provision. They disputed the trial courts’ characterization of their claims as operating as “de facto regulation” of greenhouse gas emissions. They also contended that their claims were actionable under Maryland law.

City of Baltimore lawsuit seeking to hold fossil fuel companies liable for climate change impacts.

Mayor & City Council of Baltimore v. BP p.l.c.

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Maryland Municipalities Filed Opening Brief in Appeal of Dismissal of their Climate Cases Against Fossil Fuel Companies

Filed

United States of America

Maryland

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An aim to achieve a quantifiable outcome within a given time-frame, set by an institution such as a national government.

Policy instruments are techniques or tools used by governing authorities to promote certain policies in order to achieve predetermined goals. Put simply, instruments are how a government tries to achieve its goals, with this taxonomy being focused on national policy instruments.

Risk is the potential for adverse consequences resulting from the dynamic interplay between (climate-related) hazards, exposure, and vulnerability of affected human or ecological systems.

Groups  of people who are adversely affected by climate change or the response to it

A set of principles, processes, and practices that build economic and political power to shift from an extractive economy to a regenerative economy.

Justice is the ethical and political framework that addresses fairness, including issues of responsibility, rights, and structural inequity.

Renewable energy means all forms of energy produced from renewable sources in a sustainable manner.

Fossil fuel is a generic term for non-renewable energy sources such as coal, fossil gas, and oil (including crude oil, and petroleum products), that can be used for electricity and heat generation. Fossil fuels are hydrocarbons formed from pressurised and heated organic material buried over millions of years.

Molecules in the atmosphere that play a key role in the greenhouse effect by trapping heat radiating from Earth’s surface.

Area of the economy in which actors engage in identical or related activities.

In human systems, the process of adjustment to actual or expected climate change and its effects, in order to moderate harm, increase resilience or exploit beneficial opportunities. In natural systems, the process of adjustment to actual climate change and its effects; human intervention may facilitate adjustment to expected climate change and its effects.

The management and allocation of funds, assets and investments to meet various objectives

Financial support to help individuals manage the effects of unexpected events, securing their livelihoods and increasing the resilience of people and businesses to the changing climate. It’s especially vital in developing regions where everyday risks, climate-related weather extremes, or crop failures can push people into poverty. Without insurance, people may have to resort to selling assets or cutting consumption to cope with losses.

Codes and standards are regulatory instruments that specify minimum standards to protect health and safety. This ranges from performance standards, which prescribe outcomes while allowing flexibility to achieve compliance, to the more prescriptive approach of technology-specific standards.

Actions or measures to adapt freshwater systems to climate change.

Actions to adapt human health, healthcare systems and well-being to climate change.

Actions or measures to adapt freshwater, coastal and marine systems to climate change.

Hot temperature extremes are daily maximum temperatures  that were exceeded on average once in a decade or once in 50 years, and includes heatwaves.

The release of heat-trapping gases, primarily from human activities such as burning fossil fuels, agriculture and industry.

A long-lived, colourless gas, chiefly emitted from fossil fuel combustion, deforestation and cement production.

Actions to reduce emissions in energy generation and supply.

Risks to the ecosystem health of the marine environment, including ocean warming, ocean acidification, and ocean deoxygenation, harming biodiversity, species health, ecosystem services, and coastal community livelihoods.

Extreme weather refers to events where a weather variable exceeds (or falls below) a threshold. Meaning it is significantly different from the average or usual weather pattern.

Terrestrial means "of the earth" and relates to the risks to ecological system that includes all living organisms and their interactions within land-based environments, such as forests, grasslands, and deserts.

Air pollution involves harmful contaminants in the air, affecting both indoor and outdoor environments. It can lead to health issues like respiratory diseases and heart problems, and climate impacts such as global warming. Pollutants can damage plants, trees, habitats, and water bodies like rivers and lakes.

Oil is a combustible liquid fossil fuel composed mainly of hydrocarbons, occurring as crude oil and refined into petroleum products such as petrol, diesel and kerosene.

Fossil gas, commonly known as natural gas, is a fossil fuel consisting chiefly of methane with smaller amounts of other hydrocarbons and trace gases, found in underground deposits.

woman and genders outside of the gender binary

Any compulsory, unrequited payment to the government levied on corporations or individuals. This can be for environmental reasons, such as introducing a Carbon tax to set a price that emitters must pay for the greenhouse gases they emit.

The activities of industries that transforms raw materials into finished goods through industrial processes.

This sector involves activities to move goods and people, alongside the storage of products.

This sector creates and distributes information and entertainment through television, radio, print, and digital platforms.

Activities of government agencies and institutions that provide public services, enforce laws and manage public resources.

Activities that relate to the production of goods and services from forests.

This sector involves the distribution, treatment, and conservation of water resources.

Climate change can have a range of impacts on technological system. Extreme weather events can cause infrastructure failures like power outages or damage to roads and bridges, as well as the impacts from waste following natural disasters. Human activities also cause technological impacts, such as the risks posed by oil spillage and leaks.

Any substance with chemical properties that can cause physical harm to people or damage the environment, including ammonia, carbon monoxide, phosphine, chlorine, arsenic, cadmium, mercury, pesticides, dioxins, microplastics, benzene, asbestos, aflatoxins, fluoride, methanol, and toxins from marine sources.

Slow onset events evolve gradually from incremental changes over many years or from increased frequency or intensity of recurring events. As defined in the Cancun Adaptation Framework (2010), slow onset events include risks and impacts from rising temperatures, desertification, biodiversity loss, land and forest degradation, glacial retreat, ocean acidification, sea level rise, and salinization.

Heavy precipitation refers to any form of weather where substances fall from the sky, including rain, snow, sleet, or hail.

Maryland Municipalities Filed Opening Brief in Appeal of Dismissal of their Climate Cases Against Fossil Fuel Companies

Policy instrument

Risk

Impacted group

Fossil fuel

Greenhouse gas

Economic sector

Adaptation/resilience