Nothing is more important than the air we breathe, the health of millions of Americans, and the nation’s environment. The passage of the Clean Air Act (CAA) Amendment in 1990 demonstrates the salience of these issues, as Congress was able to undergo years of oversight hearings and intense floor debates to eventually put into law these monumental air pollution controls. These revisions to the CAA has played a crucial role in reversing the effects of acid rain, urban air pollution, and toxic air emissions (EPA, 1990). This amendment has also demonstrated how political polarization does not always put legislation in gridlock, it can instead become an effective agreement that doesn’t meet completely in the middle between two extremes. The CAA exemplifies how legislation can earn broad support from both parties by making compromises that stay focused on achieving the ultimate goal. Nevertheless, the politics surrounding this legislation also has strong implications that the Presidency plays an important role in the position and passage of the policy proposal. In addition, a members’ policy position ultimately falls under the influence of interest groups or industries that support their campaign. It is often times a members’ priority to be re-elected, thus the need for campaign money or to cater to the needs of his or her constituency drives a congress member to take their stance.


The CAA has been through a decade-long battle of difficult negotiations and is known to be the toughest environmental law in American history. The enactment of the CAA in 1970 established the first system in the federal government to regulate and control air pollution (EPA, 2017).  However, by 1989 the need for a broad overhaul of the CAA became more endearing as urban areas in particular were still violating the air-quality standards for ozone, which began to pose serious health risks to Americans. The only other major amendments added since the establishment of the CAA was in 1977 lead by Paul Rogers, who enforced the law by cutting down on vehicle tailpipe emissions (Waxman, 2009). The necessary provisions Congress needed to make in order for states to keep up with federal air-quality standards and protect the public health was long overdue. Between 1977 and 1981, many efforts to revise and extend clean-air provisions had been blocked by the political conditions of the 1980s. Strong opposition from key legislators such as Byrd, the majority leader in the Senate; and Dingell, a champion of the auto industry and the chairman of the House Committee on Energy and Commerce stalled any acid-rain legislation at the time. Furthermore, President Reagan’s commitment to reducing environmental legislation and resisting against any regulatory or legislative action on clean-air posed a difficult challenge (Simon & Al, 1995). As a result, the CAA failed to limit the emissions of air toxics caused by industrial facilities and the effects of weak environmental laws were becoming more visible across the nation. These new concerns about the environment added public urgency, thus prompted members of congress to take action.

In 1989, the incoming Bush administration was a pivotal moment in the decade-long battle for clean air. Not only did President Bush distinguish himself as the “environmental president”, he also supported the rewrite of the CAA by offering his own comprehensive clean air bill. Another important factor was the change in Senate majority leader from Byrd to George Mitchell of Maine who was a transformative actor in bringing policymakers and public attention to the acid rain issue. Mitchell was known as the policy entrepreneur (Kingdon, 1984) for his profound involvement in the policy process as the central actor in the debates in Senate and negotiations with the White House (CQ almanac 1990 ). In addition, many supporters outside of the government, including Scientists and Environmental Activists, such as Gene Likens, influenced the legislation by raising public awareness and policy process of the acid-rain issue (Simon & Al, 1995). Although this legislation faced many hurdles along the way, the strategies used in the legislative process paved the way for the bill to earn broad support from both parties.

Process in Congress

Clean Air Act 1990 in the Senate

The 101st United States Congress was a divided government with the Democratic congressional majorities under Bush’s Republican administration. Although Bush’s campaign platform pledged to have moderate democratic support, he still maintained his conservative base. The Senate held 100 seats (56-D; 44-R) with strong opposition from Midwestern Democrats and conservative Republicans, splitting the Senate on cost issues over acid rain cost-sharing, motor vehicle emissions controls and health standards for toxic air pollutants (CQ almanac, 1990 ). The bill was referred to the Senate Environmental Protection Subcommittee, chaired by Max Baucus who introduced the bill. The majority leader in the Senate, George Mitchell, was a strong supporter of passing the legislation even if it was weakened. He was committed to keeping the bill on the floor until it was finished, but soon pulled the bill off the floor to allow backroom negotiations between the Bush administration and a group of 15 key bi-partisan senators.  On March 1st, the Senate and White House negotiators delivered their new clean air agreement (S 1490), revealing a weaker bill than the initial committee measure recommended by environmentalists. This new Bush proposal was more acceptable to industry and business lobbyists, as well as filibuster-prone senators. The new clean air agenda was seen as a compromise and encompassed four major changes to the bill provisions: acid rain, smog, toxic air pollutants, and ozone depletion federal regulation (CQ almanac, 1990 ).

Bush countered against the congressional Democrats who preferred a clean-air legislation that was stronger than the version he proposed.  This was the turning point in President Bush’s role in the legislation, now a major hurdle in passing a stronger and more comprehensive bill. To demonstrate the best option Congress has to overcome this hurdle, we will use “backward induction” to figure out the strategic move of President Bush, the last player first, and then that of the committee, who has first-mover advantage to determine what’s the best option. Since President Bush prefers L5 to the status quo, he will choose to veto when the committee bill is anywhere to the left of L4 or to the right of L5. If the committee chooses to put the bill between L4 to L5, then Bush will support the bill. As a result, the committee will choose to report a bill in any region where the administration will support the bill, which is between L4 to L5.

Before the passage of the bill, Bush made clear threats to veto the Senate’s legislation if they made changes that will increase the cost by more than 10 percent greater than his proposal, as well as outlining twenty-four priorities for amending the Senate version of the bill (Bryner, 1993). Senate leader Mitchell was in a united front with other key senators to support the bipartisan version and warned senators that the deal-breaker amendments could destroy the CAA altogether if the White House decides to veto, as demonstrated in Figure 1. In order to prevent further risk of compromising the White House-approved deal, Mitchell persuaded the Senate to a Unanimous Consent Agreement to limit the debate to an up-or-down vote. On April 3rd, the Senate bill (S 1630) eventually passed with overwhelming support (89-11) , however the bill was substantially weakened to conform to Bush’s proposal.

Clean Air Act 1990 in the House

The House held a Democratic majority (267-D; 167R) with more House members in support of stronger clean-air legislation than in the Senate. The Health Subcommittee Chairman, Waxman has been one of the forcing drivers in pushing the CAA to the floor of the house with strong support for extensive provisions governing auto emissions. On the other hand, Dingell was an auto industry ally who had a history of stalling any bills that would enforce new standards on automakers.  Dingell and Waxman have been long time competitors on the issue of anti-smog provisions, which posed a threat to another stalemate of the CAA in the House. The strategy to deal with this hurdle is to use median voter theorem, influencing the fundamental voters that would make or break the legislation.

Using the spatial voting model, we can understand why Waxman needed to convince the medium voters. In Figure 2, the median voter (L4) given the ideal positions of Dingell and Waxman, will choose to vote for Dingell’s proposed legislation. However, if Waxman negotiated with these voters and proposed a bill just to the of L3, then Waxman will win their votes to pass the legislation. In reality, Waxman worked towards convincing two key voters, Tom Tauke, an Iowa Republican and Ralph Hall, a conservative Democrat. Waxman spent time with both congressmen to find a position in the legislation that would meet both of their needs. Dingell, on the other hand, soon realized that he did not have the votes to win on an issue that was so important to him. For the first time in more than a decade, Dingell was willing to sit down with Waxman to negotiate the best deal for his constituents. The agreement was through conference, making it more likely to succeed since no changes could be made in the Senate. The committee voted 38-2 on March 22nd, which neutralized disputes over the bill’s most controversial sections on defining the methods for controlling air pollution.  From then on, Waxman and Dingell were compelled to find further agreements to work together.

Another major hurdle in the House was the interregional division between Midwestern states and “clean states” that made it difficult to achieve goals in improving the acid rain provision. Midwesterners wanted cost-sharing to help bear the costs of meeting acid rain controls, while a much larger group of “clean state” members did not want to pay. The best strategy to overcome this, as seen in the previous example on antismog provisions, is to forge a compromise between the Midwesterners and clean states. Dingell and Waxman managed to finally bring the CAA to the floor after years of stalemate between the two legislative powerhouses, a pair no one would ever expect.

Clean Air Act 1990 in the Conference Committee

In the final stages of negotiation, the House and Senate were very close on many major issues, however the two differed significantly on the topics of stratospheric ozone depletion, permits and enforcement. One of the major concerns in the conference was the possibility of Dingell taking advantage of the limited time, which could force a trade-off by holding a bill hostage to calendar and weakening the bill in conference. Another major hurdle was the White House administration’s careful watch over the bill in conference, which could make it difficult for the House and Senate to be able pass stronger legislation.

Although the Bush administration played an active role in negotiating the Senate bill, they made a detrimental miscalculation that the House would submit a weaker bill. Without the administration’s careful watch over the House, they were able to come up with a stronger bill. Furthermore, White House negotiators expected the Senate bill to keep its participants only through the floor vote, not through subsequent House-Senate conference which allowed senators to vote however they wish. Since the senate election was coming soon, members found this to be a great opportunity to bring home an environmental victory when seeking re-election. Senators had an incentive to support the strongest provisions in both bills, especially with public pressure in support of seeing these changes. The House voted (401-25) to approve the conference report, and the Senate subsequently voted (89-10). The significant milestones from this legislation was creating programs for acid deposition control, controlling toxic pollutants, as well as phasing out the use of chemicals that deplete the ozone layer. This contributed to the prevention of many premature deaths, and hospital admissions for respiratory and cardiovascular illnesses. In addition, the legislation created permit program requirements, and expanded enforcement of these regulations. In spite of the bill straying away from President Bush’s initial version, he signed the legislation that Congress had been working on for 16 months, establishing one of Congress’s monumental historic achievements.


The Clean Air Act amendments of 1990 has been one of the hardest fought legislative battles in Washington, nevertheless the drastic improvement in environmental standards today have proven it to be effective. The politics surrounding the legislation has illustrated how a President is able to use their power to threat a veto in order to pass legislation in line with their preferences. In addition, strategies to overcome political polarization is possible when both sides are willing to make compromises and be persistent in negotiating. The shift in Waxman and Dingell’s relationship from being adversaries to partners proves the committee’s ability to pass bills acceptable to opposite groups. Lastly, environmental lobbyists can also trigger public interest and demand for stronger environmental action, which has added pressure to Congress. Members prioritize their ability to be re-elected, so support from their home state is important. This landmark legislation serves as a reminder that despite the push-back from members of Congress and the White House, necessary changes can be made through strategic plotting and persistence.