Careers

Diversity

With 18 offices, from New York to Los Angeles and Seattle to Orlando, we live and work in communities all over the U.S., collaborating across locations, disciplines and even borders. Our experienced, highly ranked lawyers serve businesses wherever they are and wherever they want to go.

Offices

About Us

Pages

Professionals

Thought leadership: blogs, podcasts, videos, publications, events and news

Insights

Practices & Industries

Pro Bono

Home | BakerHostetler

Artie McConnell Presents on Safeguarding Aerospace & Defense Supply Chains Webinar

Nicholas Carson, Christina Novotny Present ‘Tax Credits/Incentives Under the Inflation Reduction Act’ to Tax Club of Cleveland

Erica Nordberg Joins <em>Citywealth</em> Leaders List: Top 40 Washington DC Wealth Advisors and Manager 2026

Data Counsel

Video Game Consoles and the Texas App Age Assurance Law

Mark has been recognized by Chambers USA for environmental litigation (2015 to 2026) and has been named by Law360 as one of the "Top 5 Environmental Attorneys Under the Age of 40" on two occasions.

core/freeform

J.D., Harvard Law School, 2004, 

B.A., University of Florida, 2001, 

<ul>
<li>The Legal 500 United States (2019)
<ul>
<li>Recommended in Environment Litigation</li>
</ul>
</li>
<li>Chambers USA: Environment in the District of Columbia (2015 to 2026)
<ul>
<li>Band 4 (2021 to 2026), Band 5 (2017 to 2020), Up and Coming (2015 to 2016)</li>
</ul>
</li>
<li>Law360 “Rising Star” in Environmental (2016)</li>
<li>Law360 “Top 5 Environmental Attorneys Under the Age of 40”</li>
<li>Martindale-Hubbell: AV Preeminent</li>
<li>Washington, D.C., Super Lawyers
<ul>
<li>“Super Lawyer” (2018 to 2020)</li>
<li>“Rising Star” (2014)</li>
</ul>
</li>
<li><em>The Best Lawyers in America® </em>(2026 to 2027)
<ul>
<li>Washington, D.C.: Environmental Law</li>
</ul>
</li>
</ul>


Washington, D.C.

BakerHostetler Attorneys Named as <em>The Best Lawyers in America</em>® for 2027

BakerHostetler Secures Precedent-Setting OSHA Victory for ExxonMobil

Chambers USA Guide 2026 Recognizes 179 BakerHostetler Attorneys and 81 Practice Areas

BakerHostetler Attorneys Named 2026 Best Lawyers, Ones to Watch and Lawyers of the Year

Chambers USA Guide 2025 Recognizes 171 BakerHostetler Attorneys and 73 Practice Areas

Chambers USA Guide 2024 Recognizes 155 BakerHostetler Attorneys and ­66 Practice Areas

Years of Litigation in High-Profile Defamation Case End with Favorable Result

Chambers USA Guide 2023 Honors 147 BakerHostetler Attorneys and Recognizes 64 Practice Areas

BakerHostetler Team Named Environmental Group of the Year by Law360

BakerHostetler Attorneys Make Significant Gains in The Legal 500 Annual Guide

Chambers and Partners USA Honors 127 Attorneys and 43 Practice Areas in 2019 Guide

<i>Chambers and Partners USA</i> Honors 118 Attorneys and 45 Practice Areas  in 2018 Guide

BakerHostetler talks with <i>USA Today</i> about the SIPA Trustee’s fourth pro rata interim distribution; states Madoff Recovery Initiative nears $6 billion in distributions to allowed claimants

Law360 article on SCOTUS Request for DOJ Opinion on SIPA Trustee’s Petition for Writ of Certiorari names BakerHostetler attorneys

BakerHostetler’s settlement with JPMorgan Chase and the ongoing Madoff Recovery Initiative Discussed on National Public Radio’s <i>All Things Considered</i>

BakerHostetler appears on NPR’s <i>All Things Considered</i> to discuss Madoff Recovery Initiative; host Robert Siegel interviews SIPA Trustee Irving Picard and his Chief Counsel David Sheehan

Madoff Recovery Initiative surpasses $5 billion in distributions to allowed claimants; CNBC’s Scott Cohn discusses latest recovery with BakerHostetler’s SIPA Trustee Irving Picard and his Chief Counsel David Sheehan

Services

Commercial Litigation

Litigation

Environmental

Appellate and Major Motions

Political Law

Industries

Energy

Energy Litigation

Clean Air Act

Critical Minerals

<h5>Trial and Appellate Litigation</h5>
<ul>
<li>Lead trial counsel or co-lead trial counsel in numerous federal court trials.
<ul>
<li>Co-lead trial counsel in four-week jury trial defending journalist against claims of defamation brought by a prominent scientist. The jury ruled in the client’s favor on half of the at-issue statements and awarded nominal damages amounting to only 0.01% of the plaintiff’s demand on the remainder. After trial, the Court awarded over $450,000 in attorney’s fees and sanctions to the journalist and co-defendant.</li>
<li>Lead trial counsel in an action obtaining permanent injunction barring the enforcement of state law binding delegates to national party conventions to the results of a presidential preference primary.</li>
<li>Lead or co-lead trial counsel for inventor in three federal court trials to obtain patents. Judgment that the inventor was entitled to a patent in all cases.</li>
<li>Co-lead trial counsel representing inventor in bench trial on whether the inventor was barred by prosecution laches from obtaining multiple patents.</li>
</ul>
</li>
<li>Represented parties in appeals throughout the U.S. and argued numerous appeals in the Second, Third, Fifth, Seventh, Eighth, Ninth and District of Columbia Circuits.
<ul>
<li>Lead counsel to Petitioner in U.S. Supreme Court litigation concerning regulation of carbon dioxide under Clean Air Act NSPS program. Supreme Court ruled in favor of Petitioner in landmark decision recognizing the major questions doctrine.</li>
<li>Argued appeal on behalf of international client in a case involving the production and sale of MetaBirkin NFTs by a designer that infringed the client’s trademarks protecting its brand of handbags both in name and appearance.</li>
<li>Argued appeals on behalf of manufacturers in support of affirmance of a decision dismissing a citizen suit alleging violations of the Clean Air Act preconstruction permitting program.</li>
<li>Argued an appeal on behalf of a nonprofit organization in support of affirmance of a preliminary injunction stopping a criminal investigation.</li>
<li>Argued an appeal on behalf of employer challenging an NLRB decision recognizing labor organization.</li>
<li>Argued an appeal in support of the reversal of a decision confirming labor arbitration awards.</li>
<li>Argued a challenge to a decision revising approval of a state implementation plan arising out of the Clean Air Act greenhouse gas regulation.</li>
</ul>
</li>
<li>Represented parties and <em>amici curiae</em> in proceedings before the U.S. Supreme Court and nearly all of the U.S. Courts of Appeals.
<ul>
<li>Represented an <em>amicus</em> group composed of all former Secretaries of Defense and members of the Joint Chiefs of Staff in an appeal of a decision denying qualified immunity to former Secretary of Defense Donald Rumsfeld, helping secure a rehearing en banc.</li>
<li>Represented an <em>amicus </em>group of law professors before the U.S. Supreme Court supporting a petition for <em>certiorari </em>and merits proceedings in a global climate change public nuisance suit against electric utilities.</li>
</ul>
</li>
</ul>
<h5>Environmental Regulatory Proceedings and Litigation</h5>
<ul>
<li>Represented state and private clients in Clean Air Act administrative proceedings and litigation, including preparing comments on proposed actions and contesting them in courts of appeals. Has extensive experience in actions concerning climate change, air quality standards, emission standards, preconstruction and operating permits and state implementation plans.
<ul>
<li>Represented a petroleum refinery in litigation concerning EPA’s denial of a small refinery hardship waiver from the Clean Air Act Renewable Fuel Standards program.</li>
<li>Counseled a petroleum refinery on compliance strategies for the Clean Air Act Renewable Fuel Standards program, including RIN retirement requirements.</li>
<li>Represented a petroleum refinery in enforcement litigation concerning alleged violations of Clean Air Act NSPS and NESHAP programs.</li>
<li>Represented a manufacturing company in administrative and federal court litigation defending the validity of its preconstruction and operating air permit. Judgment entered for manufacturing company in all cases.</li>
<li>Counseled a leading electric utility on Clean Air Act compliance strategy and the potential legal implications of climate change for the U.S. industry.</li>
</ul>
</li>
</ul>
<h5>Media and First Amendment</h5>
<ul>
<li>Represents journalists, media organizations and nonprofit entities in First Amendment litigation and counseling.
<ul>
<li>Obtained summary judgment for a nonprofit entity against claims of defamation brought by a prominent scientist. The Court ultimately awarded over $500,000 in attorney’s fees, court costs and sanctions to the nonprofit entity and a co-defendant.</li>
<li>Represented a media organization against claims of defamation brought by an election systems manufacturer arising out of coverage of legal challenges to the 2020 election.</li>
<li>Represented a leading publisher against claims of defamation brought by former Congressional employees.</li>
</ul>
</li>
</ul>
<h5>Political Law</h5>
<ul>
<li>Counsels businesses, political committees and nonprofit entities on compliance with campaign finance and ethics law requirements.</li>
<li>Represented clients in litigation concerning campaign finance requirements.
<ul>
<li>Obtained a preliminary injunction barring the enforcement of a state law requiring certain social welfare organizations to register as political committees.</li>
<li>Obtained a preliminary injunction barring the enforcement of a state law barring coordination between candidates and unaffiliated organizations concerning issues advocacy.</li>
<li>Argued an appeal seeking affirmance of a decision enjoining a criminal investigation into alleged state campaign finance violations.</li>
</ul>
</li>
</ul>


Mark W. DeLaquil

Mark W. DeLaquil

Experience

Recognitions and Memberships

Insights and News

Credentials

Areas of Focus

Industries

Services

Featured Insights