Under the federal Family and Medical Leave Act (FMLA), an eligible employee may take leave to care for a covered family member, including a parent. A "parent" under the FMLA includes a biological, adoptive step or foster mother or father, or any other individual who stood in loco parentis to the employee when the employee was a son or daughter (e.g., under 18 years of age, or over 18 years of age an incapable of self-care due to a disability). 29 CFR 825. 122(b). In loco parentis means that the individual had day-to-day responsibility to care for or financially suport the employee when the employee was a son or daughter. 29 CFR 825.122(c)(3). Therefore, the parental relationship need not be legal nor biological.
To invoke the protections of the FMLA, the employee must notify his or her employer of the need for FMLA-qualifying leave. A lot of litigation surrounds this issue of notice and whether a sufficient amount was given to the employer by the employee in order to evoke the protections of the Act. The FMLA's notice requirements are not onerous. Basically, the employee must provide adequate information to the employer that the leave may be in need of FMLA leave. An employee doesn't even have to use the term or words "FMLA" to evoke protections. If the employer needs more information to determine whether the leave is covered by the FMLA, they are required to inquire further.
It is utterly important that an employee seeking FMLA leave pursuant to In loco parentis provide enough information to their employer to show the type of relationship required to take the leave--especially if there isn't a legal or biological relationship. Absent a legal or biological relationship it isn't always obvious that a person serves as a parental figure to qualify the employee for FMLA leave and that could get the employer off the hook in a subsequent suit.