Jennifer Bonjean said her client's Eighth Amendment rights against cruel and unusual punishment are being violated in federal custody at the Metropolitan Detention Center in Brooklyn.
Well-known inmates, including convicted sex trafficker Ghislaine Maxwell, are often put on suicide watch, said Bonjean, who insisted her client wouldn't harm himself.
"MDC Brooklyn is being run like a gulag," Bonjean said. "My partner and I spoke with Mr. Kelly following his sentencing, he expressed that he was mentally fine, was behaving appropriately and was eager to pursue his appeal."
Suicide watch typically means a prisoner is placed in a bare-bones cell and issued a tear-resistant, one-piece smock to wear. It also often includes increased observation from guards.
Donald Murphy, a spokesman for the Bureau of Prisons, said Friday that he could not specifically address the conditions of Kelly's confinement.
"For safety and security reasons, the Bureau of Prisons does not provide information about conditions of confinement or internal security practices for any particular inmate," Murphy said.
"The BOP is committed to ensuring the safety and security of all inmates in our population, our staff and the public. Humane treatment of the men and women in our custody is a top priority. "
Three years ago, federal officials came under considerable scrutiny when convicted sex offender and millionaire financier Jeffrey Epstein, who was accused of abusing dozens of underage girls, died by suicide in his Manhattan jail cell.
Epstein had been taken off suicide watch in the days before his death.