And because the minimum standard can vary dramatically so too will costs vary dramatically. So youre having the epa consider costs before the epa can know what the costs are. Your honor if i can respond to that before the other question at the other end of the bench, epa does know what the costs are through the rulemaking process in which it undertakes notice and comment with respect to both the m1a determination and the Emission Standard. Section 7607 d1c of the Clean Air Act lists subsection n as one of the provisions that requires notice and comment rulemaking und your the special Clean Air Act procedures. And this is why the agency explained that theres no final m1a until the end of the process, until notice and comment, and weve taken and determined what the costs are. And this is then confirming what Justice Breyer said. The point that you had an opportunity and apparently took advantage of it to tell the epa that it should subcategorize this source. And it decided to subcategorize just one piece of it. So what youre really saying to us is its not the listing its the way theyve set up their emissions standards that i disagree with because they could have decided that there were subcategories that didnt require standard at all. Im presuming that they could have said anybody by the water doesnt have to do more because theyre already part of the 12 , were going to do cost by everybody else thats not by the water. Conceptually, your honor i imagine they could have subcategorized away the entire industry. But thats not what they did in this rulemaking. And with respect to certain of the regulations no, they didnt do it but youre asking us this is almost this is a challenge to a regulation thats only piecemeal. Because youre arguing that they should have considered cost, but they obviously did before they issued the standards. You cant look at the standards and the emissions and the listing in a case like this in isolation. Justice sotomayor, if i could try the answer to the question once again. Subsection m1a question is if after considering results of the study, and i know the study looks at alternative control strategies for any emissions that may warrant regulation. The agency determines such regulation is appropriate and necessary. So the focus of the determination is not on listing and whatever may flow from that but the regulation that the agency decides to apply to address the remaining Public Health hazard that is identified from this source category. Mr. Brownell did epa say we are not going to take costs into account at the listing stage because we will take costs into account through this subcategorization possibility thats being discussed . No, they did not, your honor as i recall the record of the proceeding this discussion of subcategorization has come up in the briefing. Why didnt they write you see whats brothering these questions are difficult because theyre so hypothetical. It isnt true that 50 of the industry will use up 50 all the gross domestic product, et cetera. But they wrote this thing in a way that sounds as if even though that had been true they wouldnt have taken that into account. So what they say is the epa does not prove it is appropriate to consider crosswind in determining whether e. G. U. Is you see the problem for me. But esg is telling us dont worry. Maybe they should have written knowing what we know and what is undisputed so far we dont think that the cost problem is big enough for to us warrant a costbenefit analysis or other consideration. Okay. Then theyve taken it into account. So theres no problem. If its reasonable. Thats why im looking to see its really the sg. But is there really a different way that they could eliminate this horrible scenario if it existed, which it didnt. You understand what im driving at . Im trying to get your best answer on that. And i want to emphasize that this is not an argument about whether or not to regulate mercury where theres been an identified Public Health risk. Its whether the Regulatory Regime that has been defined here under section 7412, which the government says is the listing that applies to all other source categories and the d3 minimum control Technology Standards that apply to all other source categories is the right way to do it. Regardless of how you subcategorize, its going to have tremendous impacts as a result of acid gas regulation and for a pollutant that presents no Public Health risk. We cant uphold an agency rule on a ground that they didnt adopt below, correct . Thats correct. Under chennerly. So is your understanding correct that this is not an argument, a basis for decision that they adopted below . Thats correct, your honor. My understanding of the basis for the decision below is that costs are irrelevant in a determination under m1a, whether or not whether to regulate this source category under the typical subsection 7412 regime that applies to other sources. Exactly right, mr. Brownell. The agency at that point in time was only answering the very first question. The very threshold issue. And at that point the agency said costs were irrelevant. But costs become relevant later in the analysis. And in a variety of ways through the 12 1 2 , through the 12 . Through the categorization and subcategorization. Through the determination whether to raise standards even higher. So costs costs, costs later. But as to this particular thing the agency said yes here we dont consider costs. We could but we dont want to because theres all this potential for costs to come in afterwards. And your honor, its costs costs, costs. Under the statutory criteria that congress provided for setting d3 control Technology Standards and then having to find those standards at the end of the process. The agency finallizes its m1a determination in light of the costs and impacts and other factors that are mentioned. Do you think that whenever the term appropriate is used in a regulatory context in the Clean Air Act that it demands a costbenefit analysis . Your honor when you say in any context thats so broad i dont think that i can say that it would require costbenefit in any context, but in the specific context here where the focus is on whether such regulation is appropriate or necessary, that regulation has certain characteristics and consequences that weve talked about this morning including the fact that it imposes on a pollutant that presents no Public Health risk 5 million a year. Before you finish because your time is up can you clarify for me why this is at this stage something we should be concerned about because there is this Regulatory Impact assessment that i said that the benefits vastly exceed the costs. And thats an Impact Analysis that has gone through the process and they concluded the epa appropriately calculated the costs. The cobenefits, all of those benefits are cobenefits. Only 4 to 6 Million Dollars are associated with has the air pollutants. Those cobenefits that are in the Regulatory Impact analysis were not considered as part of the regulatory determination for good reason because theyre important questions regarding their legal importance and relevance under the proper standard. And what i mean, your honor, is that pm 2. 5 is the pollutant. Fine particles that is associated with these cobenefits. That is extensively regulated under the National Air QualityStandard Program. Those air quality standards were only recently revised to be tightened. And in the context of that proceeding the agency found that the low levels of exposure for these cobenefits did not produce effects or risks that were of regulatory significance because theyre too uncertain. There were serious questions about legal relevance and importance. Thank you counsel. Thank you mr. Chief justice. Section 7412 m1a should be affirmed for three basic reasons. First, it is the most natural and certainly a permissible reading of the statutory text that directs epa to focus on Health Concerns and doesnt mention costs. Second, it harmonizes the provision with section 7412s structure and design because it applies the same regulatory logic to power plants that congress directed epa to apply to regulate hazardous air pollution from every other type of source and that is to decide whether to list for regulation based on health and environmental hazards alone and consider costs in setting the Emission Standards. And third, as a matter of common sense and sound government practice it was certainly appropriate for epa to list power plants for regulation based solely on health and environmental hazards because that reflects the approach congress chose not only in 7412 in this Regulatory Program but in all of the major Regulatory Programs under the Clean Air Act. Now that you have three outs your first point you concede, dont you, that epa could have interpreted the statutory language to allow them to consider costs . I think epa read it as read the best interpretation of the statute was it didnt provide for the considerational costs at the listing stage. If you adopted a regulation that said appropriate and necessary allows us to consider costs, you think that would be appropriate . I think the phrase appropriate and necessary doesnt by its terms preclude the epa from considering costs. But under chevron what the epas got to do is explain the justification for its reading of the statute. Since youre dealing with the term as capacious as appropriate and since you could have issued a regulation allowing the consideration of costs as appropriate, youre saying that the agency deliberately tied its hands and said were not going to consider something, were going to issue a rule saying were not going to consider something we could consider otherwise . I think the best way to think about this mr. Chief justices what the agency did was decide that it was appropriate to approach the question of whether to regulate power plants in the same manner that Congress Found it was not only appropriate but mandated. I understand your argument they could have done that. But i think its unusual for an agency to say when they want to do something that thats the only thing we could do. Agencies usually like to maintain for themselves as much discretion when they can. It strikes me as unusual maybe the agency could go ahead and not consider cost. But it say that were prohibited from considering costs under the phrase appropriate it strikes me as very unusual. I dont think so mr. Chief justice. It said didnt say were prohibited from considering costs. It said we are not going to consider costs at the listing stage in making a decision about whether power plants should be listed for regulation under section 7412. I thought the rule was that the phrase appropriate and necessary did not allow them to consider costs. And appropriate and necessary goes to the question of whether power plants should be listed for regulation under section 7412 which would then kick in the regulatory mechanism by which standards were set and costs were considered at the standard. I had the same question for mr. Chief justice. Let me ask one more time. Could this agency reasonably have considered costs at stage 1 . I dont think the statutory text unambiguously forbids them from considering costs. But they determine the best reading of the statutory text is power plants after the study was conducted that congress required, epa determined that power plants are no differently situated than any other source of hazardous air pollutants regulated under section 7412. If i may. Yes. And for every other source of hazardous air pollutants what Congress Mandated as appropriate was that you do not consider costs when you decide whether to regulate, you only consider health and environmental effects and then you do consider costs under section 7412d and you set the emissions standard. How is that consistent with this statutory scheme . If your argument is that epas only reason for doing this is that it wants to treat our plants the same as other sources we know that thats what congress didnt want or it would have it would not have enacted a separate provision for power plants. I agree justice alito, that Congress Proposed different treatment for power plants. But that doesnt answer the question. That just asks the question. The question is what different treatment did congress prescribe . Now, what petitioners are arguing is that what congress prescribed and mandated was a costbenefit analysis that does not apply to any other source of hazardous pollutants. But thats not what the text or statute says and thats not what the history reflects. What the text of the statute says in 1a is even though for every other source regulation would proceed immediately, for power plants there was uncertainty about whether power plants emitted hazardous pollutants at a level that would cause problem, whether the acid rain regulations would solve the problem, and whether there were alternative control strategies available. This if i may, im sorry. Yeah, sure. What Congress Told epa to do was to study those three things. Those go to health considerations. And then once epa made a judgment about that it was to decide whether to list power plants for regulation, whether it was appropriate, necessary to list them for regulation. This is what i dont understand about your position. At least to hold open the possibility that power plants would not be listed even if their emissions exceeded the levels that would result in listing for other sources. I dont see another reason why they would treat them differently. I think if i could just continue. You may disagree with that. But it seems to me that thats a necessary inference from the statutory scheme. If that is the case what factor might congress have thought would justify allowing power plants tomeit more than would be permitted if there were other sources . Now, the petitioners have an explanation, which is costs. And they say that power plants have to bear a lot of costs that other sources dont have to bear. In particular the title 4 program. Their emissions might exceed the otherwise permissible limit because they have participated in the cap and trade program. So they have contributed to the reduction in emissions in that way in a way that wouldnt be reflected in there. In their own emissions. So that is an explanation. Cost is whats missing. I dont know what your explanation is. I know your honor asked me to accept the premise but i cant accept the premise because both the text of m1a and the legislative history tell you what krgsz Congress Left open. And they were all related to the possibility of health hazards. The argument that your honor just posed is not in the legislative history and its not in the text. And if Congress Really thought that then what they would have said to epa is push the pause button, take the three years and study, dont subject them to the same schedule as everybody else, and study the cost problem. They would have expressly told epa to study cost and they did not do that. If all they were concerned about was health why wouldnt they impose on power plants the same standard thats imposed on area sources . Just ask epa to determine whether there is i forget the exact term. But is there an effect on Public Health, a significant effect on Public Health, whatever if so list. I think they came very close to that because what they said first of all, they told epa to make its judgment after considering the results of the study and they told epa to study things that went to health hazards. So that comes very close, it seems to me, and reason it used the appropriate and necessary language rather than the language your honor suggests is because congress when it was legislating here in 1990 understood that there might well be uncertainty at the end of of the Analysis Congress directed the epa to undertake, mr. Tl might be uncertainty about the projected effects of the acid rain regulations. I think thats what the legislative history said. I do want to clear up a misconception about that i think. Which is that the way these acid rain regulations unfolded they were put in place in 1990 at the same time as 7412. But they were to unfold over a tenyear period. Five years until the first stage and then five more years until the second stage. So epa was going to have to make a longterm projection here about which there could be some uncertainty. So i think what congress was saying toechlt pa was you may need to exercise your judgment. And in fact epa did exercise its judgment because it concluded there are two parts to this argument. One is were they thinking of if it wasnt costs. I see your answer to that. But the second which i think your argument very much depends on in my mind anyway is dont worry because there is a way to take into account costs. So if in fact i mean you know, its a lot of money, 9 billion. And if you divide it by the population you have 30 a person or a family of four of 120 thats a lot of money for people. For some people. And if you say, gee, you couldnt take it into account ever, it could have been 500. It begins to look a little irrational to say im not taking it into account at all. But to say never fear. Because they will take it into account when they set standards. And at that point i read the thing about the 12 . Ive got the word similar source, which then can refer me back to the categorization of two things earlier as i say maybe, and then i have aside from that hey heres what you do. When youre regulating, you look at the top 12 generators and thats the minimum standard. So they may want to say thats not right. I mean, its right. It says it. But if you go to the bottom 50 generators youre going to see its not going to cost 120 per family, its going to cost 1,000 a family. And we have the epa saying we wont even look at that. At that point i begin to say oh my goodness, why . Why wont you even look at it . You can say it isnt true. But why wont you even look at it . And now the answers seem to me to be in that word similar source and the classes and the subcla