In denying summary judgment to the employer, the court in Kesler v. Barris, Scott, Denn & Driker, PLLC, No. 04-40235, 2008 U.S. Dist. LEXIS 31577 (E.D. Mich. April 17, 2008) found that employer questions to employees while on FMLA leave and employer requests that an employee perform work duties while on FMLA leave "are sufficient to constitute an FMLA interference claim is supported by relevant case law."
Comment: While an employee is on FMLA leave employers would be well-advised to avoid contacting the employee on work-related issues. Asking or requiring the employee to perform work while absent on FMLA leave is simply out of the question.
Some courts have allowed a de minimis amount of employer contact (e.g., where is a file type questions) without finding an FMLA violation. The more contacts, and/or the more extensive the contacts, the more likely that an employer will be found to have interfered with the employee's FMLA rights.