Resident Lisa Muzi presented the council with a petition signed by more than 700 residents in opposition to the tower.
Jay Stroman, vice president for advancement at Young Harris College, said as trustee of the property, the college is committed to maintaining its value. A cell tower, he said, could diminish the property value by as much as half, he said.
The college assumed ownership of the property in July, following the death of the former owner whose family had been working with T-Mobile.
City council members pointed out that the proposed site is in one of Johns Creek's last rural areas and contains numerous historic sites. They also said they were not convinced the company explored alternatives to the site.
In its court filing, attorneys for T-Mobile said the company performed all the studies and met all the requirements set out in the city's ordinance. It further acceded to any conditions for landscaping and buffers recommended by the planning staff.
The council's decision, the company attorneys argued, was made in bad faith and has caused T-Mobile unnecessary trouble and expense.
Representatives from Johns Creek and T-Mobile would not comment on the litigation.