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Mark Diehl Sullivan

Mark Sullivan’s client reviews

     5.0 stars 15 total

Review Mark Sullivan

  • 5.0 stars

    Posted by Stephanie

    Hired Attorney


    Happy with the result of my workers comp case, he did a great job as my lawyer. He's very understanding and patient. Definitely hire him to be your lawyer and you're going to be in good hands.

  • 5.0 stars

    Posted by Lonnie


    Mark did a very good job of educating me in the process. He was instrumental in getting what I needed from Wyoming Worker's Compensation. He was very knowledgeable and provided fantastic arguments.
    He contacted me when said he would and conducted himself as nothing but professional. I think his patience with me was more than exceptional. I questioned everything and he knew the answer or would find it for me. I would and have recommended his services to others.

  • 5.0 stars

    Posted by Carole

    Mark Sullivan tackles the most frustrating legal issues with skill and integrity.

    Our organization hired Mark Sullivan four years ago. We needed legal advice on some longstanding and ongoing issues. We were impressed with how quickly he grasped the facts and provided options. Mark did not try to rush us to litigate but rather encouraged a non court solution. Once it was clear that was not to happen, he advised us on other paths. Mark was clear about the issues, estimated the costs, length of time the effort might take and guided us with dignity and expertise through the processes. We prevailed in each case. Having Mark as our attorney gives us great peace of mind.

  • 5.0 stars

    Posted by Bob

    Our Go-To Lawyer

    Mark has served as my company’s legal counsel for the past five years. During that time he’s helped us successfully navigate a wide range of vexing legal issues including implementing our stock option plan. I find Mark exceptionally easy to work with- he’s sharp, responsive and, when necessary, hard-nosed. Perhaps even more importantly, he knows how to rein-in my sometime irrational urge for legal confrontation when it’s not in the company’s best interest. I recommend Mark without reservation.

  • 5.0 stars

    Posted by Thomas

    Clever, Cunning, Efficient, and Excellent Communication

    I can't be specific, but I hired Mark Sullivan at least three times in 5 years to help in an ongoing intellectual property dispute, which thanks to Mark is no longer "ongoing." Its over! With carefully calculated negotiations and round table toughness, Mark successfully took on a team of opposing lawyers and won for me a favorable settlement. Later he showed thorough knowledge of the law and keen resourcefulness, not only quelling opposition attacks, but also winning for me a greater reward than either of us expected. If you are looking for an attorney who knows the law, knows how to use it, and can work effectively and efficiently on your behalf, I would highly recommend Mark Sullivan.

  • 5.0 stars

    Posted by a Contracts client

    After a long case lasting over a year...

    Outstanding attorney - showed integrity, grit, extensive knowledge and intelligence, humility but with strength and aggressivness.
    Have worked with multiple other attorneys... Mark's responsiveness and attention to detail were by far the best.
    These qualities along with the outcome of the case would definitely lead to using him again and recommending him to others.

  • 3.0 stars

    Posted by a Workers Compensation client

    Was not impressed.

    Did not respond to my emails in some instances, although he's really a pleasant attorney he was not be diligent in my Wyoming Worker's Compensation case. In other words did not pursue or key points in my case. He could have done better, and would not appeal my case. He said that a lawyer wants to keep in good terms of judges, and that's why he would not appeal my case.

    Mark Diehl Sullivan’s response: “This was a very difficult workers' compensation claim. While I understand the client's frustration at the result, the hearing officer at the administrative level issued a sound ruling, well-supported by the facts and the law. As I explained to the client, an appeal would have been futile. I do want to remain on good terms with our local judges and would not bring a meritless appeal. That is particularly true in the context of a workers' compensation claim where the state bears the attorneys' fees and costs. Pursing a meritless appeal would have been unethical.”
  • 5.0 stars

    Posted by Arik

    I highly recommend Mark to my business peers

    Mark's great advice, forethought, and actions helped my company quickly collect a debt from a delinquent client in a way that was firm, respectful, and effective. Because of Mark's intelligent approach and preparation for all contingencies in what was shaping up to be a very difficult debt collection, we were able to avoid going to court or even threatening to do so.

    Mark is great to work with and a true professional.

    Thank you, Mark!

  • 5.0 stars

    Posted by Scot & Gary

    We are SOO grateful to Mark, and would highly recommend him to anyone.

    We have hired Mark on 3 separate occasions; twice to review minor issues for us, and once for an extremely large problem that was potentially devastating. We last hired Mark to help us (and another great attorney, Richard R. Thomas, of Scottsdale, AZ) with a complex commercial litigation case involving a $Trillion multinational corporation with unlimited legal/financial resources.
    We have known other lawyers with big egos and control issues. Not Mark. He is great to work with! Mark collaborated with our other attorney extremely well. Additionally, he welcomed our input as clients, and worked closely with us every step of the way.
    This was a particularly complex and challenging case that required attorneys to do detective work and extensive research. Whatever Mark didn't already know, he learned or figured out; he didn't just stick with strategies he was familiar with or had previously employed. Mark was impressively thorough! Further, his preparation for hearings, depositions, etc. was not only noteworthy, but admirable. Mark's high levels of professionalism, ethics, and true integrity served us well; and, we believe, added even more credibility to our case in the eyes of the judges. It is our opinion that any judge, jury, arbitrator, or mediator will not only like Mark, but, most importantly, really respect him.
    Mark's billing practices have been very fair, and he has deserved every penny. Mark has heard our "thank you's", witnessed our tears of joy, and has felt our genuine hugs... and there is still gratitude we have yet to express for what he has done for us.
    While we are hoping to never again be involved in any type of lawsuit, we would, without hesitation, put our trust in Mark D. Sullivan again.

  • 5.0 stars

    Posted by Pauline

    Recommended wholeheartedly & without reservation

    The case Mark handled for me and my husband was a breach of contract, fraud and racketeering case involving multiple plaintiffs against a modular homebuilder that had closed up shop, leaving us all with partially-completed but fully-paid-for homes.
    Mark's representation of us included a hearing in Cheyenne in which we were seeking a preliminary injunction freezing the defendants' assets which were in danger of being liquidated.
    Ultimately, thanks to Mark's expert advice, we elected to have him guide our case through mediation, and we successfully avoided going to court. Without Mark's tireless efforts, his impeccable professionalism, and--perhaps most importantly--his vision in bringing racketeering charges to bear in the case, our outcome would likely have been very different. We remain profoundly grateful for Mark's comprehensive evaluation of our complaint, his faith in the strength of our case, and the herculean effort he exerted on our behalf. We recommend him wholeheartedly and without reservation.