IT Consultancy Contract Lawyers for Illinois

Michael has extensive experience advising companies from start-ups to established publicly-traded companies . He has represented businesses in a wide array of fields IT consulting, software solutions, web design/ development, financial services, SaaS, data storage, and others. Areas of expertise include contract drafting and negotiation, terms of use, business structuring and funding, company and employee policies, general transactional issues as well as licensing and regulatory compliance. His prior experience before entering private practice includes negotiating sales contracts for a Fortune 500 healthcare company, as well as regulatory compliance contracts for a publicly traded dental manufacturer. Mr. Brennan firmly believes that every business deserves a lawyer that is both responsive and dependable, and he strives to provide that type of service to every client.

I am a solo-practitioner with a practice mostly consisting of serving as a fractional general counsel to growth stage companies. With a practical business background, I aim to bring real-world, economically driven solutions to my client's legal problems and pride myself on efficient yet effective work.

Experienced business advisor and in-house counsel with extensive litigation experience, representing parties in a variety of complex commercial disputes, including securities, financial fraud, contract, and antitrust litigation.

I provide practical, plain-English legal guidance to solopreneurs and small businesses who want to build strong foundations and make informed decisions with confidence. With 20+ years of experience—including 16 years in-house advising senior and executive leaders—I bring the insight of a trusted legal partner who understands how legal strategy supports long-term business growth. My clients walk away feeling supported, seen, and empowered. They know I genuinely care about their success and bring more than just legal knowledge—I bring a coach’s mindset, a problem-solver’s lens, and a commitment to helping them protect what they’ve worked hard to build. Whether you’re reviewing contracts, forming your business, protecting your brand, or need ongoing legal support, I’m here to deliver clear, actionable guidance and solutions that fit your business.

I received a bachelor’s degree in philosophy from Northwestern University in 1996 and then got my JD at University of Illinois College of Law in 1999. I have been a lawyer helping people with legal issues in the United States and Internationally since then. That includes drafting and reviewing contracts. I am also passionate about helping small and medium businesses with trademark registration and trademark-related legal projects. The law can be confusing and complicated for people, and I am passionate about providing professional legal services to my clients while simultaneously making the legal process less confusing and stressful for them. My goal is to help clients navigate through both good and difficult times by tailoring my skills, experience, and services to their specific needs.

Navy veteran with 15 years experience practicing law in Chicago.

Financial Services, Business, Corporate, Personal Injury, and Healthcare. I've represented fortune 100 companies and defended individuals in personal debt litigation. Wide breadth of experience, ready to assist.

2008 - Present: Sole Practitioner – Dennis W. Winkler, P.C. Practice primarily in finance and business transactions, as well as commercial real estate transactions. Represent developers, investors, lenders, and businesses, in such matters as: corporate entity selection, drafting and negotiating complex asset purchase agreements, corporate mergers and sales, stock purchase agreements, and various other business contracts for closely related businesses. Involved in a variety of real estate developments, multi-family apartment buildings, construction and acquisition financing, commercial leasing, sophisticated workout transactions, joint ventures, and tax-deferred exchanges. Advise on tax and other savings incentives available to business owners and real estate owners in Illinois. Advise companies involved in related real estate activities such as sales, leasing, property management, brokerage, and construction. Tax experience that includes the representation of taxpayers in State and Federal controversies including: sales/excess tax disputes and responsible parties’ tax assessment protest. Additionally, Dennis has experience in the protest of real estate taxes of commercial and multi-family real estate. As a legal and business advisor, Dennis is committed to helping clients find, develop, and close deals that further their business objectives. Dennis regularly advises entrepreneurs and closely held businesses on matters incidental to their day-to-day business operations as well as their capital raising and start-up needs, corporate structure, private equity raises, and operating agreements. Much like general counsel, Dennis’s breadth of experience allows him to not only provide strategic planning and routine business transactional support to companies, but he also regularly advises on a number of unique issues facing companies by spotting issues and engaging specialists when needed, such as intellectual property, environmental, and bankruptcy counsel. As such, Dennis has been actively involved in sales and acquisitions of manufacturing companies, trucking companies, and logistics companies.

Senior experienced contracts/transactions attorney in the Software Technology space. Also very versed in general corporate legal matters relating to business operations.

Commercial Litigation attorney providing advice and counsel to management regarding employment related matters and risk management issues