Tanko-Yakassai was arrested by the Department of State Services shortly after criticizing President Muhammadu Buhari on Twitter.
Falana in a statement on Sunday titled “Asking Buhari to resign is not an offense” condemned the arrest of Yakassai.
He recalled that Buhari and other chieftains of the All Progressives Congress (APC) were not arrested when they demanded the resignation of former President Goodluck Jonathan.
Falana stated that since such concerned citizens were never arrested, the harassment of Yakassai is high-handed, discriminatory, and illegal.
Falana demanded the immediate and unconditional release of Mr Tanko-Yankassai from illegal custody.
He however noted that if the State Security Service has evidence that the “political detainee” has committed any criminal offence known to the law, then he should be transferred to the police for proper investigation and possible prosecution.