Can an employer force an employee to resign?

In MacLean v. City of St. Petersburg (M.D.Fla. 2002) 194 F.Supp.2d 1290, the district court granted summary judgment in favor of the defendant employer in a Title VII action, finding that, unless "the employer forces the [employee's] resignation by coercion or duress" or "obtains the resignation by deceiving or misrepresenting a material fact," an employee's resignation is "presumed to be voluntary," and, therefore, the employer's "failure to accept [the employee's] rescission of her voluntary resignation [is] not an adverse employment action." (Id . at p. 1299.)