Attorney Ellen Girard Giorgiadis of Quarles & Brady wrote a nice brief discussion about leave as an accommodation under the Americans with Disabilities (ADA) and the Equal Employment Opportunity Commission's (EEOC) continued attack on employers with strict attendance policies upheld against individuals who may need more than the 12-week leave provided under the Family and Medical Leave Act (FMLA).
While it may be hard for some people to imagine that an employer may be found to have violated the ADA for not allowing an employee to be off work for more than 12 weeks, the EEOC and some courts have found this to be a reasonable accommodation and several cases the EEOC has prosecuted have resulted in multi-million dollar settlements:
Back in August 2011, the EEOC had a panel discussion on the topic which prompted an article in the Wisconsin Law Journal on Wisconsin's case law on leave as a reasonable accommodation. Then, back in April 2012, the 9th Circuit decided a case that held the plaintiff's attendance was an "essential job function" and that adjusting an employer's attendance policy was an unreasonable accommodation for purposes of the ADA--though it is important to keep in mind this was a fact-specific case.
Until Courts provide more guidance for employers to follow, it is best to be flexible and engage in the good 'ol interactive process when attendance becomes an issue for a disabled employee.