Peter A. Lassiter

Peter A. Lassiter, Attorney at Law
Peter A. Lassiter
With 14 years of experience as a prosecuting and defense lawyer, Peter brings his professional experience & personal accountability to every client.
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About Peter

  • Over 14 years of experience
  • Former Prosecutor for almost 10 years
  • Current Military Veteran, serving in the Missouri Army National Guard
  • Serving Clients in private practice for four years
  • During this time, I’ve handled over 2,300 cases
  • Traffic Cases since 2015 – 0ver 1700 traffic matters
  • Servings counties – St Charles, Lincoln, Warren, Pike and MORE
  • In contact with over 2000 clients

Areas of Expertise

Peter’s full service firm offers family law services in the areas of dissolution, divorce, non-contested, paternity, family access, and modifications. As a family man, himself, he understands the important of healthy roles for both mom and dad to work well together for the good of the child. He is also a certified Mediator and GAL, Guardian ad Liteum. Many family law cases can be described as “heart-wrenching”. Our office knows how important it is to work hard, and too look for ways to save our clients money on these cases that can be very costly and emotional.

Protecting your family by ensuring your estate is taken care of. We can help with last will and testament, power of attorney, health care directives, beneficiary deeds and more. Estate planning services can sometimes feel uncomfortable or even unsettling. Peter approaches this with compassion and care. The goal with estate planning is to ease stress and worry and make sure you and your family are well cared for. Peter offers a free initial consultation, because every family’s needs are different. In that consultation, he is able to get to know the needs and concerns he should focus on when developing legal documents for you.

Starting your own business? The challenges are many but the rewards are great! Peter is ready & willing to help with your new adventure.
First, he meets with potential clients and works through any areas of concerns, potential needs or connections, and if desired can help prepare contracts that might be needed. He can also help you draft and work through the proper paperwork needed by the State of Missouri or banks with small business programs.Next, we’ll schedule a time for all owners of the company to come in and finalize the Operating Agreement with signatures. Along with the Operating Agreement, our office will be listed as the business’ Registered Agent. Starting a new business can be a challenge but is a very exciting time. Peter would be honored to walk the journey with you!

Peter’s experience working as a Missouri Assistant Prosecutor for almost 10 years in Lincoln and Franklin Counties. He has a great understanding of the prosecutors job and how they like to work. He can put his experience to work for you, offering common criminal defense services in the areas of DWI/DUI, criminal theft, felonies, orders of protection, and more. Peter has maintained a great rapport with the prosecutors, which usually means that they will work with him closely to make sure recommendation are made and charges are amended. Ethically, our office can not and will not promise to make things “go away” but we do work aggressively for our clients and their best interest. Peter works hard to keep communication open between himself and his clients, so that cases can be resolved in a timely and efficient manner.

Through our partner firm, The Traffic Law firm of Missouri, Peter has you covered. He can help you with minor to high speed infractions, multiple offender cases, license suspension, warrants, or “failure to appear” notices. Located in Troy, Missouri, we are able to connect with you in the St. Louis/St. Charles area or beyond. For aggressive representation in your traffic law case, choose us. Get more information on our full range of services on the Traffic Law Firm of Missouri’s website (

… Accidents? Slip and fall? Dealing with increasing medical bills, doctors visits, and all those things involved with finding solutions for any medical issues that come from injuries can be very overwhelming. Peter and his staff can help work through those concerns, help our clients, get healthy, and on the road to recovery which is the first focus.

Community Involvement


  • Board of Governors Cardinal Glennon Children’s Hospital
  • Board member for non-profit Bakhita Law – specializing in Human trafficking
  • Chapter Founder and Captain for Troops of St George
  • Serves in Missouri army National guard
  • Active member of the Knights of Columbus Council
  • Board Member of Visitors for the Developmental Center
  • Missouri Army National Guard as a Judge Advocate
  • State Advocate


  • State advocate for the Missouri State Knights of Columbus
  • Board member for MOVA – Missouri victim advocates
  • Offices within the Knights of Columbus, council level, state level
  • Founder of the Patriot Day Run – In Memorial of 9/11, Supporting Backstoppers in the USO of Missouri

Education & Experience


High School

Graduated from St. Louis University High School in St. Louis, Missouri.


Graduated from St. Louis University with a Philosophy Degree.

Law School

Graduated University of Missouri Law School and began practicing law.

Missouri Assistant Prosecutor

Began work as a Missouri Assistant Prosecutor in Lincoln county. In 2009, Peter became the prosecutor in Franklin County.

Military Service

December, Commissioned as a 1LT in the Missouri Army National Guard JAG officer. In 2012 Peter completed his training for MO ARMY National Guard. In October of 2017, he was promoted to MO ARNG Captain.

Established St. Thomas Legal

Founded St. Thomas Legal, LLC. in 2014 Peter marched into full-time Private Practice with the firm he founded.


In July of 2015 - Traffic Law Firm of Missouri is purchased by St. Thomas Legal, establishing a Troy, Missouri presence. In 2015, Peter was also certificated as a Mediator and GAL, Guardian ad Litem.

Favorite Quote

“Lord, grant that I may be able in argument, accurate in analysis, strict in study, candid with clients, and honest with adversaries. Sit with me at my desk and listen with me to my client’s plaints, read with me in the my library, and stand beside me in court, so that I shall not, in order to win a point, lose my soul. Amen.” -St. Thomas More.