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Texas Board of Legal Specialization

Board Certified in Civil Appellate Law

Cassie Dallas is an experienced and adept appellate advocate, who has persuaded courts and prevailed on legal issues in appeals and mandamus proceedings in Texas state and federal courts.

Cassie is an invaluable asset to every stage of litigation from spotting potentially dispositive issues to developing a trial strategy, to determining the best venue for any case, to preserving error for appeal.

She is a talented and passionate advocate who brings a fresh perspective and collaborative approach to every case.


Cassie leads complex appeals and critical motions practice in courts nationwide. She simplifies complex issues and crafts creative arguments to end legal disputes and overturn bad outcomes. Cassie has argued and won appeals on critical legal issues and obtained early dismissals of claims in state and federal courts. In the Supreme Court of Texas, Cassie authored briefs and argued a mandamus proceeding that led to a unanimous decision overturning several intermediate courts of appeals decisions that had prevented defendants from mounting an evidentiary defense to medical expenses affidavits under an erroneous interpretation of section 18.001 of the Texas Civil Practice and Remedies Code. Cassie also authored briefs and successfully argued an appeal that resulted in the Supreme Court of Texas limiting equitable tolling of certain legal malpractice claims.

Her appeals often involve issues of first impression, and she has obtained favorable results on behalf of insurers, healthcare providers, premises owners, property- and homeowners associations, licensed professionals, and businesses. She has considerable experience preparing appellate briefs, original proceedings, motions to dismiss, summary-judgment motions, jury charges, and post-judgment motions. She handles matters across the state of Texas and has argued numerous cases before the Second and Fifth Courts of Appeal.

Other Experience

Cassie has also represented individual and corporate defendants at all stages of litigation. She has worked to resolve high-stakes business disputes, property disputes, and claims involving personal injury, premises liability, and professional malpractice.

Representative Experience

Argued and won Texas Supreme Court appeal on the issue of counter-affidavits for a major insurance provider

Won Fifth Circuit appeal in which the court upheld arbitration award for law firm client over unpaid legal fees

Won Fifth Circuit appeal in which the court affirmed dismissal of defamation and tortious interference claims brought against insurer

Won Tenth Circuit appeal in which the court affirmed dismissal of breach of contract and bad faith claims against national insurance company

Argued and won appeal in premises liability cases against national retailers and property owners

Briefed and argued successful petition for writ of mandamus, which challenged trial court’s order striking a medical expense counteraffidavit and obtained clarification from the Supreme Court of Texas on the statutory requirements for sufficient counteraffidavits and the effect of serving, or not serving, satisfactory counteraffidavits under section 18.001 of the Texas Civil Practice and Remedies Code.

In re Allstate, 622 S.W.3d 870 (Tex. 2021).

Argued and won appeal in suit to enforce deed restrictions against property owner

Argued and won appeal in health care liability claim, obtaining reversal of judgment and dismissal of plaintiffs’ health care liability claims against rehabilitation center

Won permissive interlocutory appeal and obtained dismissal of claims for bad faith, unfair settlement practices, breach of contract, breach of duty of good faith and fair dealing, and DTPA violations

Briefed and argued appeal regarding limits of equitable tolling on a legal malpractice claim in multi-party litigation in the Supreme Court of Texas.

Zive v. Sandberg, 644 S.W.3d 169 (Tex. 2022).

Won dismissal on appeal of claims against gun range based on section 128.053 of the Texas Civil Practice and Remedies Code

Won appeal and obtained dismissal of negligence and gross negligence claims against indoor trampoline park

Won appeal of summary judgment based on attorney immunity in malicious prosecution case

Won permissive interlocutory appeal in dispute between adjoining property owners regarding right of lateral support

Won appeal and obtained reversal of default judgment entered against business owner and real estate developer

Won appeal in negligent activity and premises liability case against commercial waste disposal company

Won appeal in breach of contract and bad faith case against insurer who denied coverage under policy endorsement

Won appeal in legal malpractice case on behalf of attorney who provided tax advice to estate client

Part of briefing team in permissive interlocutory appeal regarding pre-trial expert report requirement applicable to gun ranges before Second Court of Appeals and the Supreme Court of Texas.

Shinogle v. Whitlock, 596 S.W.3d 772 (Tex. 2020).

Argued and won appeal in premises liability case against property owner and property management company

Professional Recognition

Texas Super Lawyers - Rising Star

Listed for Appellate, Civil Litigation: Defense

Super Lawyers

Up-And-Coming 50: Women Texas Rising Stars Top List

Super Lawyers

Women and Up-And-Coming 100

Dallas Women Lawyers Association

VP Leadership Class

Southwestern University

18 Under 40 Award

Texas Bar Foundation


Dallas Bar Association

Women Empowered to Lead (We Lead)

Texas Board of Legal Specialization

Board Certified in Civil Appellate Law

Related Resources

Related Services

Publications & Speaking Engagements

Education, Admissions & Activities


Texas Tech University School of Law

J.D., summa cum laude, 2010
Order of the Coif
Texas Tech Law Review, Student Writing Editor
Phi Delta Phi

Southwestern University

B.A., summa cum laude, 2007
Phi Beta Kappa
English and Commutations

Bar Admissions



Court Admissions

United States District Court of Texas

Northern, Southern, Eastern, Western

United States Court of Appeals, Fifth Circuit

United States Court of Appeals, Tenth Circuit

Professional and Community Activities

William "Mac" Taylor Inn of Court

Dallas Bar Association

Dallas Association of Young Lawyer

McKinney ISD Interdisciplinary Study and Mentorship Program

Mentor, 2017

Diversity and Inclusion Committee Chair

First Court of Appeals of Texas, Justice Michael Massengale

Law clerk