Power plant releasing smoke into an orange hazy sky; the sun is setting.

Affordable Clean Energy Rule

  • April 2007

    The U.S. Supreme Court con­firmed, in Mass­a­chu­setts v. EPA, 549 U.S. 497 (2007), that the Clean Air Act applies to green­house gas­es con­tribut­ing to cli­mate change. The courts have sub­se­quent­ly held that the Envi­ron­men­tal Pro­tec­tion Agency (EPA) must reg­u­late green­house gas­es fol­low­ing the release of its 2009 Endan­ger­ment Find­ing, in which the Agency deter­mined that car­bon diox­ide and oth­er green­house gas­es pose a threat to pub­lic health and the environment.

  • August 2015

    In August 2015, EPA final­ized the Clean Pow­er Plan, which restricts car­bon emis­sions from exist­ing fos­sil-fueled pow­er plants, which were, at that time, the largest source of cli­mate pol­lu­tion in the Unit­ed States. The Clean Pow­er Plan adopt­ed a state-based approach for restrict­ing car­bon emis­sions from fos­sil-fueled pow­er plants, pro­vid­ing states with flex­i­bil­i­ty to adopt a vari­ety of emis­sions reduc­tion strate­gies, based on each state’s views of how it might best use its options to reduce car­bon emis­sions from pow­er plants.

  • Feb­ru­ary 2016

    In Feb­ru­ary 2016, the Supreme Court stayed the Clean Pow­er Plan, halt­ing it from for­mal­ly going into effect while a new round of legal chal­lenges were being resolved by the D.C. Cir­cuit Court of Appeals. State attor­neys gen­er­al suc­cess­ful­ly opposed the Trump administration’s repeal and replace­ment of the Clean Pow­er Plan with the so-called Afford­able Clean Ener­gy (ACE) rule. The ACE rule was vacat­ed and remand­ed back to the EPA in Jan­u­ary 2021.

Oppos­ing the Afford­able Clean Ener­gy” Rule

Reg­u­la­to­ry Process


  • Decem­ber 2017

    In Decem­ber 2017, the EPA issued an advanced notice of pro­posed rule­mak­ing to solic­it infor­ma­tion from the pub­lic about a poten­tial future rule to reduce car­bon emis­sions from fos­sil-fueled pow­er plants.

  • Feb­ru­ary 2018

    In Feb­ru­ary 2018, 19 attor­neys gen­er­al filed com­ments oppos­ing the EPA’s pro­posed rule­mak­ing to pos­si­bly replace the Clean Pow­er Plan, as the EPA’s pro­posed nar­row view of its author­i­ty under the Clean Air Act is con­trary to the law, and the pos­si­ble rule­mak­ing will pre­vent the EPA from tak­ing imme­di­ate action to address cli­mate change.

  • August 2018

    In August 2018, the EPA released its pro­pos­al for rolling back the Clean Pow­er Plan with a sig­nif­i­cant­ly watered down replace­ment rule, the so-called Afford­able Clean Ener­gy” rule. The pro­posed replace­ment rule is based on a nar­row and restric­tive inter­pre­ta­tion of the EPA’s author­i­ty under the Clean Air Act to meet its legal oblig­a­tion after Mass­a­chu­setts v. EPA to reduce car­bon emis­sions. Con­se­quent­ly, the plan will achieve min­i­mal reduc­tions in car­bon emis­sions because it requires only mar­gin­al effi­cien­cy improve­ments at indi­vid­ual coal plants. Addi­tion­al­ly, the pro­pos­al denies states the flex­i­bil­i­ty to pro­duce state-led plans to cost-effec­tive­ly reduce car­bon emis­sions from across the pow­er sec­tor. The day that the EPA released its pro­pos­al, the attor­neys gen­er­al of Cal­i­for­nia, Illi­nois, Iowa, Mass­a­chu­setts, Mary­land, New York, and Vir­ginia released state­ments express­ing their oppo­si­tion to the pro­pos­al and vowed to con­tin­ue to defend the Clean Pow­er Plan.

  • Sep­tem­ber 2018

    In Sep­tem­ber 2018, the EPA announced it would hold one pub­lic hear­ing in Chica­go, Illi­nois on its Clean Pow­er Plan replace­ment plan, and that it had extend­ed the com­ment peri­od on the replace­ment plan by one day, to Octo­ber 31, 2018. With­in a week, 21 attor­neys gen­er­al request­ed that the EPA extend the com­ment dead­line by 60 days to pro­vide states suf­fi­cient time to com­ment on the com­plex and impor­tant pro­pos­al. The let­ter from the attor­neys gen­er­al also request­ed that res­i­dents of their states be pro­vid­ed the oppor­tu­ni­ty to com­ment on the pro­pos­al by hold­ing addi­tion­al pub­lic hear­ings in major geo­graph­ic areas of the coun­try, includ­ing in Cal­i­for­nia, North Car­oli­na, the mid-Atlantic, the North­east and the Pacif­ic Northwest.

  • Octo­ber 2018

    Illi­nois Attor­ney Gen­er­al Lisa Madi­gan tes­ti­fied against the Clean Pow­er Plan replace­ment plan at the Chica­go pub­lic hear­ing on the plan. Attor­ney Gen­er­al Madi­gan object­ed to weak­en­ing restric­tions on car­bon emis­sions from the coal indus­try, not­ing that the administration’s pro­posed roll­back would dam­age vul­ner­a­ble ecosys­tems in Lake Michi­gan and harm Illi­nois’ agri­cul­tur­al sec­tor. A rep­re­sen­ta­tive from the New York Attor­ney General’s office also tes­ti­fied at the Chica­go hear­ing, crit­i­ciz­ing the pro­posed replace­ment plan’s increase in pre­ventable deaths and fail­ure to mean­ing­ful­ly reduce car­bon emissions.

  • Octo­ber 2018

    On Octo­ber 31, a coali­tion of 19 state attor­neys gen­er­al led by New York Attor­ney Gen­er­al Bar­bara Under­wood sub­mit­ted com­ments to the EPA call­ing for the Agency to drop its pro­posed rule. The attor­neys gen­er­al not­ed that the EPA’s pro­posed rule is replete with fac­tu­al inac­cu­ra­cies, ana­lyt­i­cal errors, and legal flaws and, accord­ing­ly, con­cludes that the rule – if adopt­ed – would be unlaw­ful.” In a press release asso­ci­at­ed with the fil­ing of the com­ments, Attor­ney Gen­er­al Under­wood promised that if the Admin­is­tra­tion adopts this gross­ly ille­gal rule, my office will work with our state and local part­ners to file suit to block it.”

  • Decem­ber 2018

    In Decem­ber 2018, a coali­tion of twen­ty attor­neys gen­er­al sent a let­ter to EPA Admin­is­tra­tor Wheel­er, request­ing that EPA with­draw the Clean Pow­er Plan replace­ment rule in light of the Fourth Nation­al Cli­mate Assess­ment. The Nation­al Cli­mate Assess­ment, released in Novem­ber 2018 makes clear that action is need­ed now to reduce cli­mate change- caus­ing green­house gas emis­sions in order to avoid the worst effects of cli­mate change. At a min­i­mum, the let­ter urged EPA to reopen the com­ment peri­od for the replace­ment plan to allow for pub­lic input on and ade­quate con­sid­er­a­tion of the Assessment’s find­ings. Ten days lat­er the coali­tion sub­mit­ted a copy of the Nation­al Cli­mate Assess­ment to the rule­mak­ing record for the pro­posed Clean Pow­er Plan replace­ment rule and high­light­ed parts of the Assess­ment that sup­port the coalition’s sub­mit­ted com­ments on the pro­posed rule.

  • June 2019

    In June 2019, the EPA final­ized its so-called Afford­able Clean Ener­gy rule. The final rule for­mal­ized the repeal of the Clean Pow­er Plan, which would have reduced car­bon emis­sions as man­dat­ed by the Clean Air Act and the Supreme Court in Mass­a­chu­setts v. EPA.

    As it had done in the August 2018 pro­posed rule, the EPA relied on a nar­row, restric­tive and unsup­port­able inter­pre­ta­tion of the agency’s author­i­ty under the Clean Air Act, choos­ing to ignore the growth and poten­tial of clean ener­gy in deter­min­ing the best sys­tem for reduc­ing coal pol­lu­tion. The final rule requires only mar­gin­al effi­cien­cy improve­ments at indi­vid­ual coal plants and states will no longer have the flex­i­bil­i­ty to cost-effec­tive­ly reduce car­bon emis­sions from coal facil­i­ties with­in their states. EPA admit­ted that the final rule would require the expen­di­ture of near­ly a bil­lion dol­lars in annu­al costs, while leav­ing the lev­el of car­bon emis­sions large­ly unchanged.

  • June 2019

    Attor­neys gen­er­al imme­di­ate­ly stat­ed their inten­tion to chal­lenge the so-called Afford­able Clean Ener­gy rule. On the day the rule was pro­mul­gat­ed, the attor­neys gen­er­al of Cal­i­for­nia, Col­orado, Con­necti­cut, Illi­nois, Iowa, Mass­a­chu­setts, Michi­gan, New Mex­i­co, New York, North Car­oli­na, Ore­gon, Wash­ing­ton and Wash­ing­ton, D.C. released state­ments express­ing their oppo­si­tion to the final rule as incon­sis­tent with the EPA’s respon­si­bil­i­ties under the Clean Air Act and envi­ron­men­tal­ly harm­ful. Cal­i­for­nia Attor­ney Gen­er­al Becer­ra host­ed a press con­fer­ence in San­ta Bar­bara that same day with Col­orado Attor­ney Gen­er­al Weis­er, Iowa Attor­ney Gen­er­al Tom Miller and Ore­gon Attor­ney Gen­er­al Ellen Rosen­blum in which the attor­neys gen­er­al com­mit­ted to chal­leng­ing the law­ful­ness of the final rule in fed­er­al court.



  • August 2019

    In August 2019, New York Attor­ney Gen­er­al Leti­tia James led a coali­tion of 23 attor­neys gen­er­al in fil­ing a law­suit in the D.C. Cir­cuit chal­leng­ing the law­ful­ness of the so-called Afford­able Clean Ener­gy rule. The attor­neys gen­er­al of Cal­i­for­nia, Col­orado, Con­necti­cut, Hawaii, Illi­nois, Maine, Mary­land, Mass­a­chu­setts, Michi­gan, New Jer­sey, New York, North Car­oli­na, Ver­mont, Vir­ginia, Wash­ing­ton, Wash­ing­ton, D.C. and Wis­con­sin released state­ments in sup­port of the law­suit oppos­ing the final rule that will set back attempts to reduce cli­mate change-caus­ing car­bon emissions.

    The peti­tion of review was con­sol­i­dat­ed with oth­er chal­lenges to the so-called Afford­able Clean Ener­gy rule by pub­lic health groups and coal pow­er plants. 

  • Octo­ber 2019

    In Octo­ber 2019, the coali­tion of 23 attor­neys gen­er­al filed a motion to inter­vene in the chal­lenges brought by pow­er com­pa­nies to pro­tect the EPA’s author­i­ty under sec­tion 111 of the Clean Air Act to reg­u­late green­house gas emis­sions from exist­ing pow­er plants. The coal com­pa­nies are chal­leng­ing the legal author­i­ty – sec­tion 111 of the Clean Air Act – upon which the EPA relied on to issue the Clean Pow­er Plan in 2015.

  • April 2020

    In April 2020, the coali­tion of attor­neys gen­er­al filed their open­ing brief in the lit­i­ga­tion in the D.C. Cir­cuit. The attor­neys gen­er­al not­ed that repeal­ing the Clean Pow­er Plan under­cuts the Clean Air Act’s objec­tive of reduc­ing pol­lu­tion and that replac­ing it with the so-called Afford­able Clean Ener­gy rule is unlaw­ful. The coali­tion high­light­ed that the ACE rule achieves only triv­ial emis­sions reduc­tions, while increas­ing car­bon emis­sions and oth­er pol­lu­tants in more than a dozen states; impos­es rigid restric­tions on state com­pli­ance plans; and exempts exist­ing gas-fired plants from car­bon emis­sions reg­u­la­tion altogether.

  • Octo­ber 2020

    In Octo­ber 2020, the D.C. Cir­cuit heard oral argu­ments on the chal­lenge brought by the attor­neys gen­er­al against the ACE rule.

  • Jan­u­ary 2021

    In Jan­u­ary 2021, the D.C. Cir­cuit sided with the attor­neys gen­er­al in issu­ing an opin­ion that vacat­ed the ACE rule and remand­ed the rule back to the EPA to devel­op a new rule con­sis­tent with the Clean Air Act that will reduce car­bon pol­lu­tion from pow­er plants. The court reject­ed the EPA’s argu­ment that it had to repeal the Clean Pow­er Plan and pro­mul­gate the replace­ment ACE rule, find­ing that the agency had mis­tak­en­ly inter­pret­ed its author­i­ty under sec­tion 111 of the Clean Air Act to reg­u­late car­bon emis­sions from pow­er plants as much nar­row­er than the agency’s actu­al author­i­ty under the statute.