Prosecution witness and Madison Police Captain John Stringer told the Alabama federal court in Huntsville that "force is supposed to be proportional to the threat and circumstances."
Stringer appeared at the court for the trial of former Alabama police officer Eric Parker, 26, who was charged with violating the civil rights of the 58 year old Sureshbhai Patel in the US state of Alabama in February.
Stringer said that during controlled takedowns, officers are supposed to decelerate the fall to minimise injury, Al.com news website reported.
When asked for his opinion on the technique Parker employed, Stringer said, "I thought it was improper. I saw no indications of resistance, active resistance or aggressive resistance."
Stringer, who oversees training at the department, said that leg sweeps are not taught to new officers. Parker faces up to 10 years in prison on the federal charge if convicted.
Patel, who does not speak English, was taking a morning walk when a neighbour called police to report a suspicious person. During a confused exchange, Parker slammed Patel to the ground, leaving him in need of emergency spinal surgery.
The Department of Justice argued that Patel committed no crime, presented no threat and did not pull away and that Parker's actions were unreasonable.
Meanwhile, Defense Attorney Robert Tuten argued that Patel by law should carry his green card with him at all times and Madison didn't provide adequate self-defence training to Parker, "We can't punish officer Parker because there was a language barrier."
Assistant US Attorney Robert Posey argued that failure to understand English is not the same as failure to obey an officer, "Parker acted as though the man was intentionally disobeying him."
Tuten said Parker was taking steps to control a suspect, "This was an officer safety issue and nothing other than that."
The incident occurred on the morning of February 6 when while walking down the sidewalk, Patel "was violently assaulted by a police official without provocation, and left partially paralysed," the 11-page lawsuit had said.
On February 5, Patel had arrived in the US to assist his son and daughter-in-law in caring for their 17-month-old child who suffered a developmental delay after a premature birth.