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United States Primer

Table of Contents

System of Government
Political Parties

Relevant Court Cases



United States system of government

House of Representatives
Executive branch
Supreme Court
US legislative process
Divided and unified government
Budget reconciliation


The United States Federal Government consists of three branches: the legislative branch (the United States Congress), the executive branch (including the office of the President) and the judicial branch (including the Supreme Court).

Separation of powers & checks and balances

The US government is designed such that no one branch has too much power. To this end, each branch has the ability to check the powers of the others.

  • Congress has the power to remove the President from office and confirm or reject the President’s nominations for heads of federal agencies. The Senate must approve by simple majority the President’s nominations for Cabinet members and confirms the President’s nominations for Supreme Court Justices;
  • The President has the power to veto legislation from Congress (which Congress can override with a two-thirds majority in both the House of Representatives and the Senate) and nominates heads of federal agencies, Cabinet members and Supreme Court Justices;
  • The Supreme Court is able to determine laws to be unconstitutional.



The United States Congress is the legislative branch of the American government and is comprised of the Senate and House of Representatives. Congress is responsible for making laws, and it also has the power to remove a president from office, declare war and approve or reject presidential nominations for heads of federal agencies, federal judges and the Supreme Court.


House of Representatives

The United States House of Representatives, also referred to simply as the House, is comprised of 435 elected Representatives. It is the lower chamber of Congress. The number of Representatives is spread across all 50 states and is distributed in proportion to each state’s population as measured by the US Census. There are also non-voting delegates who represent the District of Columbia and the five US territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the US Virgin Islands. Representatives are directly elected by American citizens. A Representative’s term is 2 years, and there is no limit to the number of terms a Representative can serve.



The United States Senate is comprised of 100 elected Senators, two from each US state. It is the upper chamber of Congress. The Vice President acts as president of the Senate and has the power to cast a tie-breaking vote should the chamber be equally divided. Senators are directly elected by American citizens. A Senator’s term is six years, and there is no limit to the number of terms a Senator can serve.


Executive branch

The executive branch carries out and enforces laws and includes the President, Vice President, the Cabinet and most federal agencies. The Cabinet consists of members that advise the President, who the president nominates and who must be approved by a simple majority of the Senate. The President nominates justices to the Supreme Court and heads of federal agencies and also has the ability to veto legislation created by Congress. The President and Vice President are elected by American citizens through the Electoral College. A President’s term is four years, and a President is only allowed to serve two terms. A Vice President’s term is also four years, but there is no limit to the number of terms as Vice President one can serve.


The Supreme Court

The United States Supreme Court is the highest court in the country. It forms part of the judicial branch of the federal government, which interprets the meaning of laws, applies laws to cases and determines if laws violate the US Constitution. The judicial branch is headed by the Supreme Court and consists of other federal courts as well. The Supreme Court is comprised of nine justices who are nominated by the President and receive life-time appointments. All Supreme Court Justice nominations must be approved by the Senate. Most cases reach the Supreme Court on appeal, the majority of which comes from federal courts. Appeals can reach the Supreme Court from state courts if the case in question deals with federal law. Supreme Court rulings cannot be appealed to a higher authority.


Legislative process

Below are the steps for how a bill becomes a law in the United States:

1. The bill is drafted

A bill can be drafted by both Senators and Representatives. The primary Congressperson supporting the bill is the “sponsor” and all supporting members are the “co-sponsors.”

2. The bill is introduced

The sponsor then introduces the bill. If the sponsor is a Representative, the bill is introduced in the House. If the sponsor is a Senator, it is introduced in the Senate.

3. The bill is assigned to a committee

Once introduced, the bill is assigned to a committee in either the House or Senate for study. Both chambers have a variety of committees comprised of Congress members focused on specific topics. If the designated committee does not act on the bill, the legislative process ends here.

4. The bill is reviewed by a subcommittee

Committees organize subcommittees, which have deeper topical specialization. The subcommittee can make changes to the bill and must vote to send the bill back to the committee.

5. The bill is amended by a committee

The committee meets to make changes and amendments before recommending the bill to the House or Senate floor. If the committee votes not to report the bill to the chamber of Congress, the legislative process ends here. If the committee votes in favor of the bill, it moves to the House or Senate (to the chamber in which the bill was introduced).

6. The bill is voted on by the House or Senate

The House or Senate members debate the bill and vote to approve amendments. If the chamber does not pass the bill with a simple majority, the bill dies.

7. The bill is referred to the other chamber

Once passed by the House or Senate, the bill moves to the other chamber, where it again goes through committee review before being referred to the chamber floor for further debate and voting. If there are differences between the House and Senate versions of the bill, a conference committee may be formed that aims to reconcile those differences. If the conference committee fails to do so, the bill dies. If the conference committee reaches an agreement, it prepares a conference report with recommendations for the final bill. The House and Senate must vote to approve the conference report and then both vote to approve the bill.

8. The bill goes to the President’s desk

If the President approves the bill, it is signed into law. If the President takes no action for ten days while Congress is in session, the bill becomes law automatically. If the President takes no action for ten days while Congress is not in session, there is a “pocket veto.” If the President does not approve the law, they may veto it.

9. Congress votes to override presidential veto

If the President vetoes the bill, Congress can override the veto with a two-thirds majority in both the House and Senate, after which the bill becomes law.


Divided and unified government

A divided government occurs when the party in opposition to a sitting president controls one or more chambers of Congress. Alternatively, a unified government occurs when a single party controls the executive branch, the Senate, and the House of Representatives. Divided governments frequently present barriers to presidential action, and can make onerous the delivery of presidential campaign promises as cooperation between Congress and the President is usually needed to progress legislation. Party loyalties can create further challenges when individual politicians oppose prevailing trends or dominant ideological positions within their own party when it might aid their personal reelection campaigns.



A filibuster is any action by a member of the Senate that leads to extremely long debate times and results in either the postponement or eventual abandonment of a congressional vote. Filibusters can only be ended by a formal vote to conclude the debate, which requires a 60/100 supermajority to succeed. In other words, Senators can use a filibuster to defeat legislation that would pass with a simple majority (51/100) but doesn’t have enough support to achieve a supermajority. The filibuster has been a major obstacle to Democrats passing climate legislation, and there is growing momentum in the Democratic Party and the country to eliminate it. Democrats worked around the filibuster in 2022 by passing their premier climate legislation, the Inflation Reduction Act, through budget reconciliation


Budget reconciliation 

One avenue for achieving climate action in the US is through a process called budget reconciliation, which enables an expedited distribution of funds to a cause that might otherwise be stalled in Congress (i.e. the budget reconciliation process cannot be filibustered). Only policies that affect national spending or revenue may be included in this process. Because budget resolutions need only a simple majority to pass, they can be used to quickly earmark funds for things like pandemic-related recovery payments, disaster relief packages, or even consumer rebates for private solar panel installation. Through the process of budget reconciliation, climate action can be achieved by avoiding the filibuster and without eliciting excessive opposition from climate-skeptic politicians and lobbyists. The Inflation Reduction Act was passed through budget reconciliation for this reason.


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United States political parties

US politics are dominated by two parties: the Republican Party and the Democratic Party. There are two Senators and zero Representatives from third parties. In the 2020 presidential elections, third party candidates received 0 electoral college points and 1.8% of the popular vote (approximately 3 million votes). Below is a list of the four most popular political parties in the US.

Democratic party
Republican party
Libertarian party
Green party



Democratic Party

The Democratic Party is center-left and promotes a liberal ideology. It is considered the party within the two-party system in the US that seeks to take action to combat the climate crisis. Its Platform advocates for a variety of measures to address climate change.


Republican Party

The Republican Party, also referred to as the “Grand Old Party” or the “GOP,” is center-right and promotes a conservative ideology. In recent years, Trumpism has taken off and led to the creation of far-right factions within the party. Historically, the Republican Party has opposed most legislation to combat the climate crisis, especially Republicans among the far right of the party. There is growing recognition within the party that climate change is real and anthropogenic, though there is not consensus among Republicans as to how to address it. 


Libertarian Party

The third-largest party in the US, the Libertarian Party promotes a platform of limited government intervention in personal, social and economic areas. The Libertarian Platform promotes competitive free markets and property rights for environmental protection but does not directly address the climate crisis.


Green Party

The fourth-largest party in the US, the Green Party promotes a strong federal government and strongly advocates for environment and climate action and social justice. The Green Party Platform proposes a variety of measures to combat the climate crisis.


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Relevant court cases

Massachusetts v. EPA
West Virginia v. EPA


Massachusetts v. EPA

In the 2007 Massachusetts v. Environmental Protection Agency (EPA) ruling, the Supreme Court determined that the EPA can regulate greenhouse gases as “air pollutants” under the Clean Air Act, and carbon dioxide. Importantly, this ruling determined that carbon dioxide is among the greenhouse gasses classified as a type of air pollution. This case has cemented the EPA’s ability to regulate cars and trucks as well as buttressed its proposed rules for the power grid.


West Virginia v. EPA

In West Virginia v. Environmental Protection Agency (EPA), the US Supreme Court ruled to limit the EPA’s ability to regulate carbon emissions in the power sector. The 6-3 ruling is considered to have followed party lines, with the six justices considered conservative ruling in favor and the three justices considered liberal dissenting.

The decision determined that the Clean Power Plan, established during the Obama administration, extended beyond the EPA’s regulatory mandate, specifically its pushing of utilities to transition away from coal and towards renewable energy sources. While recognizing that the EPA does have authority to regulate emissions from the power sector, the decision placed restrictions on this authority. Evoking the “major questions doctrine,” the Court concluded that that no agency, including the EPA, may adopt rules transformational to the economy unless specifically authorized to do so by Congress in order to address a specific problem. The Court determined that the 1970 Clean Air Act, the legislation relied upon by the EPA in this case, lacked sufficient evidence of congressional authorization to expand the EPA’s regulatory authority. The decision affects all federal agencies and is considered a significant setback to the US’s ability to achieve its environmental and climate goals.


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This page was prepared under the Transatlantic Climate Bridge project - which is supported by the German Federal Government. Its contents are the sole responsibility of adelphi and do not necessarily reflect the views of the German Federal Government.