De Sousa, a 6-foot-9 power forward from Angola, has not played this season while the NCAA reviews his eligibility.
"Silvio has cooperated fully and completely with the investigation of his NCAA eligibility, which has now caused him to miss over half of his sophomore season," Scott Tompsett of Tompsett Collegiate Sports Law said in a statement. "Silvio came to the United States from Angola at the age of 15, and he did everything he was supposed to do and was asked to do to become an eligible student-athlete at the University of Kansas. Silvio followed the rules. He did nothing wrong.
"If adults did something illicit or against the rules, they did it without Silvio's knowledge or involvement. Their actions and conduct can be dealt with through the courts and/or the NCAA major infractions process. It's time for the NCAA to be fair to Silvio and immediately reinstate his eligibility."
De Sousa has been held out of competition since October, when former Adidas consultant T.J. Gassnola testified in federal court that he paid $2,500 to De Sousa's guardian, Fenny Falmagne.
"The University of Kansas continues to work with the NCAA staff to resolve issues concerning Silvio's eligibility," Kansas athletic director Jeff Long said in a prepared statement. "The process is ongoing, and we will continue to work closely with the NCAA staff. Our commitment to integrity and to the process is unwavering.
"While the past several months have been difficult for this young man, Silvio continues to work hard in the classroom and in practice and he has been an exemplary teammate. His patience and cooperation throughout this process have been admirable and we look forward to a resolution."
De Sousa graduated early from IMG Academy in December 2017 and enrolled at Kansas for the spring semester last season. He made his debut Jan. 13, 2018, and appeared in 20 games for the Jayhawks.