My aunt works for a nation-wide company which planned to down-size 3000 employees. Her company offered its employees an early retirement package with two years pay in wages. My aunt was planning to retire in two years anyway (She's 55 and has been working for the company since she was 18 yrs. old.), so she opted for the offer. She and several of her coworkers of equal seniority were not selected for the retirement offer, and numerous individuals with less time with the company were chosen. In the early 1990's, her company offered the same exact retirement package, and employees were primarily chosen by seniority. Unfortunately, I am not cognizant of her union's current contract with the company. In case the union agreement doesn't waive any seniority rights, my question is: Does this case have grounds for a class action suit under the protection of ADEA or its Older Workers Benefit Protection Act amendment? I appreciate any feedback on this matter.

You need to get a copy of the written retirement offer. I would hope the employer would not offer such a program without a document explaining benfits and eligibility requirements and any other special offers.
There are legal ways to deselect certain employees. One way I know of is by department for instance. If the employer is smart they have checked out what they can do legally.

Get a copy of the written offer it must tell you who is and is not eligible.
Without knowing the details it's hard to say if there might be a case. In any event, she should see an attorney only after getting all of the details.