About Sean

Attorney Sean M. Sweeney, JD MBA

I am a shareholder at Halling & Cayo S.C. where I have worked since 2008. Prior to joining Halling & Cayo, and after graduating from Marquette with my law degree and Masters in Business Administration, I ran my own law office. I took public defender appointments (to pay the rent) and worked to develop a business law practice. I thoroughly enjoyed it and earned a new appreciation for the struggles of starting up a new business. I now take an active role in managing the business of Halling & Cayo as well as guiding my clients and their businesses through the issues and disputes that inevitably arise.

I feel that my court room litigaiton experience, both for those accused of crimes early in my career, and for businesses now, has taught me not just the concept of how expensive a lawsuit can be (not just in money either) but the stark reality of it. That means I do everything I can to help businesses resolve their disputes without going to court, but I know I am more than capable of doing so if need be. I have represented clients in dozens of bench trials, jury trials, and arbitrations in his career. I have learned one universal truth, we don’t like to use the “f” word, “Fair” when it comes to litigation. No litigant feels what has brought them to be in Court is fair, instead Sean encourages his clients to focus on what we can change, managing our approach, and pushing to get the best result possible.

I live in Wauwatosa with my two boys, wife, and a dog and I enjoy brewing beer, working on cars, and playing with my kids in my free time. 

You can see my full profile here, call me directly at 414-755-5020 or e-mail me at sms@hallingcayo.com

Highly Recommend

All the work I have had done has been completed to a very high standard, communication has been excellent, and has been great value for the money. Unlike many law firms, the advice they give is truly intended to resolve the issue, not create a future revenue stream for the firm. Their flat rate billing is a good innovation also. Highly recommended.

Gary L.

LLC Formation

We had our LLC and operating agreement set up by Sean and it was a great experience. He answered ever question we had and made everything very easy to understand. We plan on having a lasting relationship. Would recommend to anyone in need of a business lawyer.

Dave H.

Excellent Legal Representation

My experience thus far with the firm and particularly, Sean Sweeney has been outstanding! Although we have yet to move the case forward officially, I have nothing but great things to say about the advice and service.

Jeffrey Brown


I am a client of Sean for few years and I am impressed with his work but most importantly with how caring he is about someone elses problems.I have also worked with others in that office and I would recommend these lawyers to anyone who is lost and needs guidance. Each one of them is helpful, professional and always available.


Trusted Advisor

Sean Sweeney & his team became a trusted advisor to me and my family by providing a valuable service to our needs. He exceeded expectations with his ability to act prudently and swiftly when called upon. I’m happy he’s on my team!

Todd Barden

Outstanding Service

I have worked with Sean Sweeney for 5+ years and find his legal acumen, service, and body of work exceptional. His legal mind and intuition is outstanding as is his commitment to excellence. I would strongly recommend him !

Jim H.

Exceeded Expectations

I am totally satisfied with the representation by Halling & Cayo Law Firm, Sean Sweeney and his team. They exceeded my expectations especially based on our authorized minimum expectations and their exceeding those by significant amounts

Bill B

Excellent Work

Sean (and his team) did a wonderful job handling my case. He kept me informed every step of the way and was always willing to answer my endless and sometimes repetitive questions!

Kathy M

Amazing Attorney

Sean Sweeney has helped us in so many ways that we can only say that he is nothing short of fabulous . From employment situations to business formations and much more, he has provided us the counseling and care that was above and beyond all we could ask. If need arises, we more than highly recommend, and will always turn to our attorney, Sean Sweeney.

Melanie Cholka

Outstanding Service & Outcome From Them On My Business Litigation Case

I can’t say enough about the service and outcome from Sean Sweeney and his team regarding my business litigation case. They went above & beyond staying focused with my various issues. The end result was exactly what I needed them for and if in the future I have any kind of issue I know I can count on them. If anyone else needs help with legal items I can’t stress enough that Halling & Cayo will get their issue handled in the best possible way.

Jay Lindseth

Excellent Lawyers

Sean Sweeney and Seth Hill helped establish my business. The process was painless and they took care of everything from the setup of my LLC, to giving me contracts to use, and guided me on scenarios I could expect. I trust them. Anytime I need to chat through something, no matter how busy they seem, I always get a prompt reply with well thought out responses.

James Pellizzi