Mark H. Horwitch



Mark Horwitch is one of Tabet DiVito & Rothstein’s Managing Members, was recently named one of the top 100 lawyers in Illinois by Super Lawyers, and is an arbitrator for the American Arbitration Association serving on its Commercial and Employment panels. For 24 years, Mark has been a trial lawyer and litigator, and he is a leading authority in Illinois in the area of trade secrets and restrictive covenants (non-competition, non-solicitation and confidentiality agreements) and cases involving emergency injunctive relief.  For employers and executives, Mark also prepares and negotiates employment agreements, separation agreements, non-competition agreements, non-solicitation agreements, non-disclosure agreements, no-raid agreements, and other restrictive covenants.

In addition to his trade secrets and restrictive covenant practice, Mark’s practice concentrates on (1) complex business litigation; (2) partnership, LLC, shareholder, and member disputes for closely held businesses and non-profit organizations; (3) representing policyholders in insurance coverage disputes with their insurers; (4) defamation and the First Amendment; and (5) professional malpractice claims involving accountants.

Mark has tried cases to verdict before juries, judges, arbitrators and administrative agencies. By combining aggressive trial preparation and argument with effective negotiation skills, Mark has compiled an outstanding record of achieving success for his clients in a cost-efficient manner.

Here are how some clients, opposing counsel, and current and former judges have described Mark:

“Unquestionably, Mark ranks with the best litigators we have retained . . . . [H]e possesses all of the qualities that a company like ours wants from its outside litigation counsel: incredibly hardworking and responsive, completes tasks in an efficient and timely manner, strong intellect, persuasive writing skills, strong oral advocacy skills, creative and a good negotiator.”  – Associate General Counsel of one of the world’s largest material handling companies.

“Mark’s trial preparation was thorough and meticulous.  All of our witnesses were extremely well prepared and our overall trial presentation was nothing short of masterful.”  – President & CEO of Illinois-based manufacturing company.

“[O]ne of the finest attorneys in Illinois.” – Current Chancery Court Judge in the Circuit Court of Cook County.

“I can say without hesitation that Mr. Horwitch is one of the finest trial lawyers and litigators that appeared before me during my time on the Commercial Calendar . . . . Mr. Horwitch represents his clients with tremendous zeal and is a forceful advocate on their behalf.”  – Former Judge of the Circuit Court of Cook County.

“Based, in large part, on Mark’s combination of tenaciousness and diplomacy in interacting with opposing counsel, we ultimately obtained a positive resolution to the case.  The best compliment that I can give a lawyer is that I continue to look forward to working with him or her in the future.  Mark is such a lawyer.”  – Vice President and General Counsel of Chicago-based information technology company.

“Mark is one of the best legal analysts and writers that I have opposed in many years.” – Former opposing counsel who is one of the leading trial lawyers in Chicago.

Some of Mark’s representative experience and cases are outlined below.

Non-Competition Agreements, Trade Secrets, and Other Employment Matters

A significant portion of Mark’s practice involves employment matters for employers and executives. In addition to his substantial trade secrets and non-compete practice, Mark also has extensive experience defending employers against employment discrimination, sexual harassment, and retaliatory discharge lawsuits and litigating claims involving breaches of fiduciary duties and breaches of executive compensation agreements. For employers and executives, Mark prepares and negotiates employment agreements, separation agreements, non-competition agreements, non-solicitation agreements, non-disclosure agreements, no-raid agreements, and other restrictive covenants.

Partnership, LLC, and Shareholder Disputes

Clients involved in partnership and shareholder disputes turn to Mark to find creative and cost-effective methods to accomplish their goals. Mark frequently represents partners, members, shareholders, and officers in “business divorce,” deadlock, and buyout negotiations and litigation. He also handles cases involving oppression of minority business owners by majority owners, including breaches of fiduciary duty, self-dealing and “squeeze-out” or “freeze-out” of minority owners.

Complex Business Litigation

Mark’s extensive business litigation experience involves prosecuting and defending commercial disputes in a broad range of areas, including contract disputes, director and officer liability, statutory and common law fraud, securities law violations, trust and estate disputes, real estate and land use disputes, mechanic’s liens, professional malpractice, claims under the Illinois Biometric Information Privacy Act (BIPA), franchising, banking, executive compensation, post-closing working capital adjustments, civil RICO, intentional interference with economic relationships, breach of fiduciary duty, trade secret misappropriation, intellectual property, and trademark infringement.

Insurance Coverage

In the insurance coverage field, Mark exclusively represents corporate and individual policyholders in enforcing their rights to insurance coverage where coverage has been denied for a variety of underlying liabilities, including employment, advertising injury and directors and officers claims. Mark has had considerable success in obtaining insurance coverage for policyholders through litigation and negotiation.

Defamation and the First Amendment

Mark’s defamation practice has earned national recognition in prosecuting and defending personal and business defamation actions on behalf of corporations, non-profit organizations and individuals. He is experienced in the litigation, trial and appeal of both personal and business defamation claims, many of which involve significant First Amendment issues.

Professional Malpractice

Mark has represented major firms in connection with a wide variety of claims brought by clients and client successors (e.g., the FDIC)., including claims relating to allegedly faulty audit work.

Representative Cases

Mark’s litigation experience and achievements include:

  • Trial counsel who obtained a jury verdict in excess of $13 million in compensatory and punitive damages on behalf of the former President and CEO of a North American subsidiary of a German conglomerate in a lawsuit involving breach of an executive employment agreement and defamation. The $13 million awarded by the jury was one of the largest jury verdicts of the year in Illinois, and it is believed to be the largest award in this type of case in U.S. history. The trial court’s judgment was affirmed by the Illinois Appellate Court, and the Illinois Supreme Court denied the defendants’ petition for leave to appeal.
  • Trial counsel in the successful representation of the managing partner of an investment partnership sued by six of the partnership’s minority partners for breach of fiduciary duty. After a five-day American Arbitration Association hearing, the three-member panel awarded the minority partners just 7.5% of the compensatory damages sought, which was approximately equal to the amount to which Mark’s client stipulated was owed and which was barely enough to cover the fees paid by the minority partners to the AAA. The panel also denied in full the minority partners’ request for punitive damages and attorney fees.
  • Trial counsel in the successful representation of a technology licensing company sued for millions and attorney fees by the exclusive licensor. After a five-day American Arbitration Association hearing, the three-member panel ruled in favor of Mark’s client and dismissed the licensor’s claim with prejudice.
  • Trial counsel for three Illinois-based companies in the largest case of its kind ever brought under the Illinois Motor Vehicle Franchise Act. Following eighteen days of fact and expert testimony before the Illinois Motor Vehicle Review Board, the Board granted all of the relief requested by Mark’s clients and awarded them all of their attorney fees and costs. The Illinois Supreme Court affirmed Motor Vehicle Review Board’s decision.
  • Trial counsel in the defense of a securities brokerage firm and its officers and employees before a three-member arbitration panel in an action alleging defamation, trade secret misappropriation, aiding and abetting and breaches of fiduciary duty.  Following a five-day hearing, the panel dismissed with prejudice all claims against the brokerage firm and its officers.
  • Defeated motion for temporary restraining order against two former employees of accounting firm and their new firm alleging misappropriation of trade secrets, breaches of non-competes, tortious interference, breaches of fiduciary duty, and violations of the Computer Fraud and Abuse Act (CFAA).  The court denied the TRO motion after an evidentiary hearing with live witnesses. Following aggressive expedited discovery and the deposition of a key third-party witness, Mark achieved a nuisance-value settlement.
  • Trial counsel for a retiring physician seeking his retirement benefits under his medical practice’s operating agreement. Following a JAMS arbitration hearing before a retired federal judge, the medical practice was ordered to pay Mark’s client his retirement benefits plus pre-judgment interest.
  • Won an arbitration for a publicly traded healthcare company in a dispute involving a post-transaction working capital adjustment. As part of the arbitration award, the opposing party was ordered to pay the arbitrator’s fees pursuant to the asset purchase agreement’s fee shift provision.
  • Represented social media company and its president against lawsuit filed by subsidiary of a multinational media conglomerate alleging trade secret misappropriation, tortious interference, breaches of fiduciary duty, and violations of the Computer Fraud and Abuse Act (CFA)A. Following Mark’s aggressive opposition to the lawsuit, a confidential settlement was obtained within 3.5 months of the filing of the lawsuit.
  • Defeated motion for temporary restraining order brought by non-profit organization against of its former board members alleging trade secret misappropriation.
  • Defeated motion for temporary restraining order brought by directors of non-profit organization against other directors alleging breaches of fiduciary duties.
  • Defeated motion for temporary restraining order against account executive accused of violating her non-compete. Following oral argument, the court ruled that her non-compete was overly broad and therefore unenforceable.
  • Represented information technology company and its president against trade secret, breach of fiduciary duty, and tortious interference claims brought by the president’s former employer. After Mark replaced the defendants’ prior counsel, we propounded aggressive expedited written discovery and achieved a confidential settlement within 3 months.
  • Represented shareholders and employee of a leading maker of mixed-mode chromatographic columns accused by company of misappropriating the company’s trade secrets, breaches of fiduciary duty, and tortious interference. After Mark replaced the defendants’ prior counsel, the plaintiffs were forced to re-plead their trade secrets claim after we successfully moved to dismiss the claim. Shortly thereafter, a confidential settlement was reached.
  • Trial counsel for a financial institution in a breach of contract case against a broker-dealer and an investment advisory firm at a FINRA arbitration hearing.  Following the hearing, respondents were ordered to pay damages, a significant portion of client’s attorney fees, and all of the costs of the arbitration.
  • Trial counsel in the successful representation of the Chicago-area’s largest non-profit organization in a trial in the Circuit Court of Cook County involving the non-profit’s role as a state contractor.
  • Secured a victory in the Illinois Appellate Court when the court affirmed dismissal of all claims of defamation against a leading Chicago non-profit business organization. The appellate court issued its 31-page published opinion relying solely on the strength of the briefs and without entertaining oral argument. In positioning this matter for a favorable appellate ruling, Mark’s client prevailed on a successful motion to dismiss in the Circuit Court of Cook County.
  • Won dismissal with prejudice of all claims brought against clients in a hotly contested seven-figure breach of fiduciary duty action brought by Mark’s clients’ purported joint venture partner which alleged that Mark’s clients failed to distribute profits in accordance with the parties’ allegedly agreed-upon formula. Successfully preserved the victory in the Illinois Appellate Court when the court affirmed the trial court’s ruling in a 27-page published opinion.
  • Trial counsel for the owner of a 58,000 square foot freezer/cooler facility pursuing breach of contract claims against a developer of industrial real estate. Case settled before jury selection after the trial judge granted a motion to bar the developer’s liability expert from testifying at trial.
  • Obtained temporary restraining order on behalf of a leading medical research organization that prohibited the organization’s landlord from repudiating the parties’ office lease, which would have devastated the organization.
  • Defeated motion for temporary restraining order brought by former employer seeking to prevent Mark’s client from working for a competitor in alleged violation of her non-competition agreement.
  • In one of the few cases of its kind nationwide, part of the TDR team that secured a permanent injunction in federal court for a global pharmaceutical and medical device company that prohibited a foreign corporation from forcing TDR’s client into an International Chamber of Commerce arbitration in Geneva, Switzerland.
  • Trial counsel for a developer of electronic trading software in its prosecution of trade secrets and tortious interference claims against a rival firm. Confidential settlement reached on the eve of trial.
  • Successfully defended the Chicago Park District at both the trial and appellate levels against lawsuits challenging the renovation of Soldier Field and the closing of the Meigs Field Airport.
  • Obtained a preliminary injunction and subsequently summary judgment in federal court against a suburban municipality in a case involving the municipality’s attempt to block large vehicle access to a proposed industrial park owned by Mark’s developer client. The U.S. Court of Appeals for the Seventh Circuit affirmed the trial court’s award of summary judgment.
  • Defended the former chief financial officer of a consumer goods company in a multi-million dollar lawsuit brought by the company’s lender alleging that Mark’s client intentionally inflated the value of the collateral upon which the lender made loan advances to the company. Mark negotiated a nuisance value settlement after persuading the lender that the allegations against his client were without merit. Mark subsequently secured reimbursement of all of his client’s costs of defense and settlement from the company’s D&O insurer after the insurer initially denied coverage.
  • Obtained summary judgment on behalf of the owner and operator of multiple special events facilities in the Chicagoland area after an insurer sought a declaratory judgment that it did not owe a duty to defend the firm’s client from claims in an underlying lawsuit. The decision provided insurance coverage to assist the client in defending the underlying lawsuit’s claims. Successfully preserved the victory in the Illinois Appellate Court when the court affirmed the trial court’s summary judgment ruling.
  • Won summary judgment on behalf of a leading non-profit business organization after its insurer sought a declaration that it had no obligation to defend the organization in connection with an underlying defamation lawsuit based on the insurance policy’s intentional acts exclusions.
  • Defended one of the country’s largest broad-line retailers against claims brought by one of its former suppliers. The supplier walked away from its suit and recovered nothing after the court dismissed the supplier’s fraud and breach of contract claims.
  • Defended a publicly traded manufacturer of tools and diagnostic equipment against defamation and fraud claims brought by its former distributors. The case settled after Mark obtained a with prejudice dismissal of the distributors’ fraud claims.
  • Obtained summary judgment on claims for securities fraud and common law fraud for the directors and officers of a software development firm.
  • Represented a former executive of a publicly traded company in an American Arbitration Association proceeding seeking to invalidate provisions in a non-competition agreement. Case settled before the arbitration hearing on terms that substantially narrowed the length and scope of the non-compete.
  • Obtained dismissal with prejudice of a defamation suit brought against an Illinois elected official.
  • Represented a Chicago lawyer in prosecuting defamation claims against another Chicago lawyer. Favorably settled defamation claims after defeating the other side’s motion to dismiss.
  • Represented a publicly traded financial services firm in its prosecution of claims of trade secret misappropriation and breaches of fiduciary duty against former executives of the firm. The case ultimately settled on terms favorable to Mark’s client.
  • Represented a Chicago-area company and its owner pursuing breach of fiduciary duty and defamation claims against one of the company’s former managers. Confidential settlement reached.
  • Represented one of the world’s largest financial institutions in litigation brought by the former employees and shareholders of Enron Corp.
  • Defended an employer in one of the largest class action hostile work environment cases ever brought in the United States Court for the Northern District of Illinois.
  • Represented dozens of employers in proceedings before the U.S. Equal Employment Opportunity Commission and similar state and local agencies.
  • Represented numerous partners, LLC members, and shareholders of closely held corporations in partnership and intra-corporate disputes.
  • Represented a Fortune 500 company in a professional malpractice suit related to environmental contamination at a manufacturing plant acquired in a merger transaction. Confidential settlement reached.
  • Defended a corporation and its former controlling officer against federal and state securities fraud claims brought by the purchaser of $115 million of credit-linked notes. Confidential settlement reached.
  • Represented a former partner of a Chicago-based law firm in a dispute with his former partners regarding the wind-up and dissolution of their law firm. Confidential settlement reached.
  • Currently represents a Chicago-area company and its president in a sexual discrimination, retaliatory discharge and defamation action brought by one of the company’s former high-level employees.
  • Currently defending a closely held corporation against shareholder corporate oppression claims brought under Section 12.56 of the Illinois Business Corporation Act.
  • Currently representing a major accounting firm in defense of lawsuit alleging negligence in connection with a failed bank.

Professional History

Mark joined Tabet DiVito & Rothstein LLC in 2005. Previously, he practiced in the litigation department of a large national law firm.

Awards & Recognition

For several consecutive years, Mark has been named as an Illinois Super Lawyer in the area of business litigation. Only the top 5% of lawyers in Illinois are selected as Super Lawyers, using a multi-step evaluation process involving a statewide survey of lawyers, independent panel research and in-depth evaluation of background and experience by practice area.


Mr. Horwitch is a magna cum laude graduate of the University of Illinois College of Law.  While in law school, Mr. Horwitch served as a judicial extern to the Honorable James Zagel of the United States District Court for the Northern District of Illinois. Also, during law school, Mr. Horwitch taught an undergraduate course at the University of Illinois on the principles of effective public speaking. Mr. Horwitch received his undergraduate degree from the University of Illinois, where he graduated cum laude and was elected to Phi Beta Kappa.

Professional and Community Involvement

Mr. Horwitch is a member of the Illinois State Bar Association.  Mr. Horwitch served on the Superintendent’s Citizen Finance and Facilities Committee for North Shore School District 112.  That committee was charged with conducting an in-depth study of North Shore School District 112’s facilities and finances and to recommend options that were presented to the broader community.

Mr. Horwitch may be reached at +1-312-762-9465 or by email at