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John Sylvester Klassen

John Sylvester Klassen

Practice areas:

Litigation, Criminal Defense

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About Me

Like many, I came to the Permian Basin initially, back in 1998, because of a job opportunity. I assumed I would spend a few years here and move on.  But my family and I attached roots and came to love this area passionately.  We are now proud and grateful to call the Permian Basin our home. We love its dynamism, the values that are exemplified by its citizens, and the graciousness of the community.

I was born and raised in Iowa.  I obtained an academic scholarship at the University of Tulsa, and graduated summa cum laude with a degree in political science in 1987.

Next, I was fortunate to spend some time in the Jesuit Volunteer Corps. I was assigned as a social worker to a community center in Mobile, Alabama, and lived in community with other Jesuit volunteers in Prichard.

I attended law school at Columbia University in New York City, where I met my wife, Stephanie.  I graduated in 1991, as a Harlan Fiske Stone Scholar.

After two years as a litigation associate at the Houston office of a national law firm, I joined the Harris County District Attorney’s Office in Houston and commenced a career as a criminal prosecutor. I worked for Texas Attorney General Dan Morales from 1995 through 1998, trying cases and supervising investigations throughout the state as part of the Prosecutor Assistance Division.

I came to the U.S. Attorney’s Office in Midland in 1998, and prosecuted federal cases in the Midland and Pecos Divisions. 

Texas Attorney General John Cornyn formed a unit dedicated to the prosecution of cybercrime in 2000 called the Internet Bureau, and I was among the initial group of lawyers hired to launch this unique endeavor.  As part of my work in the Internet Bureau, in the fall of 2001, I was selected to do a temporary detail assignment at the Computer Crime and Intellectual Property Section (“CCIPS”) of the United States Department of Justice in Washington. I was named chief of the Internet Bureau in 2002.

In 2003, I returned to Midland as Chief of the United States Attorney’s Office in Midland. For the next 12 years, I supervised the office’s myriad investigations of all manner of criminal enterprises, to include multi-million dollar white-collar fraud; racketeering; child exploitation; civil rights violations; complex narcotics conspiracies; weapons violations; and immigration offenses. I have tried dozens of cases to federal juries in Midland, Pecos, and El Paso.

I live in Midland with my wife and two teenage daughters.  We are very active in our beloved parish, St. Ann’s Catholic Church, in Midland.


Practice Areas

Licensed since 1991

  1. Litigation: 60%
    1 year
  2. Criminal Defense: 40%
    20 years


Payment Types:

Check, Credit Card

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Contact Info

Klassen Law Firm PLLC

4000 N. Big Spring St.
Suite 350
Midland, TX, 79705


TXEligible To Practice In Texas 199105/24/2015

Professional Misconduct

We have not found any instances of professional misconduct for this lawyer.
Avvo Contributions
Legal Answers
Work Experience
TitleCompany NameDuration
Assistant Attorney GeneralOffice Of The Attorney General Texas2000 - 2003
Assistant U.S. AttorneyUnited States Attorney's Office Western District Of Texas1998 - 2015
Assistant Attorney GeneralOffice Of The Attorney General Texas1994 - 1998
Assistant District AttorneyHarris County Da Office1993 - 1994
AssociateMayer Brown & Platt1991 - 1993

School NameMajorDegreeGraduated
Columbia University School of LawN/ADoctor of Jurisprudence/Juris Doctor (J.D.)1991