Andrew Craig Brunson was arrested following a failed coup in 2016 and is currently under house arrest.
He faces up to 35 years in prison if he is convicted.
Ismail Cem Halavurt said he has filed an appeal at Turkey's Constitutional Court on behalf of Brunson.
In his petition, Mr Halavurt argued that Brunson has been unjustly held for almost two years and that there is no risk of him tampering with any evidence.
US president Donald Trump has demanded Brunson's release.
In August, Mr Trump doubled tariffs on Turkish steel and aluminium imports, which helped deepen a Turkish currency crisis.
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