The lawyer Felix Damm made the statement about Schumacher's injury status in a lawsuit against German magazine, Bunte.
The magazine had reported in December, 2015, that the seven-time world champion was on path to recovery and could walk again.
Damm said Schumacher, 47, "cannot walk" more than two and a half years after the accident.
Bunte had written that Schumacher walked with the help of therapists and could raise an arm, quoting a source as.
Ex-Ferrari chief Luca de Montezemolo had earlier admitted that he did not have "good news" regarding the condition of Schumacher.
Former seven-time world champion Schumacher suffered head injuries in a skiing accident in the French Alps in December 2013 and spent six months in an induced coma before returning to his home in Switzerland to continue his rehabilitation.
"I get news about him constantly, and unfortunately it's not good," said Montezemolo.
Montezemolo did not elaborate on 47-year-old Schumacher's condition, but he added: "He was the most successful driver Ferrari ever had. He only suffered one accident in his entire career, in 1999, and it was our fault, not his.
"Unfortunately, a skiing accident ruined his life."