Diversity, equity and inclusion is all the rage in the corporate world. But seeking age diversity by appealing to a particular age group in hiring and promotions is proving to be a legal quagmire for some of the nation's biggest companies.

Pharmaceutical giant Eli Lilly and Co. is the latest to see litigation mount, following an initiative it launched in 2017 to increase millennials in its workforce. The case comes as IBM continues to fight allegations by ex-workers who allege they were fired in favor of younger workers, and as PricewaterhouseCoopers licks its wounds from a 2021 settlement in an age discrimination suit that will cost it $11.6 million.

Earlier this month, 53-year-old Lilly sales employee Monica Richards sued in U.S. District Court for the Southern District of Indiana alleging Lilly violated the Age Discrimination and Employment Act. ADEA prohibits age discrimination against people 40 and over.