Can a Health Screening Affect My Insurance Premium?

I have a question about insurance discrimination. The company I work for has well over 500 employees and is a union company.

According to our contract, which we signed early in 2014 and I wasn’t aware of until recently, it states that: before our open enrollment period in October 2015 for the year 2016, we must have a healthcare screening for the employee and spouse, along with a history questionnaire form submitted.

If we do this, we will receive a $400 discount per year on our health insurance.

What if I refuse to do this and they charge me $400 more a year for my insurance?

Doesn’t this qualify as discrimination based on health and medical history? Most of the older employees, that I know, have some sort of pre-existing condition, injuries sustained from the job and other genetic diseases in their background.

I really don’t want to do this because it could base our premiums, in the next contract, on the combined health of the employees.