Safety Knights

Depends on what you mean by "screening"? You can do pre-employment fit for duty exams to see if they're physically capable of doing the job.

I’ve set up pre-employment physical tests with an occupational health clinic. They do vision, hearing, and a fit for duty test.

I agree with what others have said. However, in the corporate world HR seems to be joined at the hip with legals who run scared of discrimination law suits. I worked for such a company for many years. It is frustrating when you know some new hires are going to be incapable of performing without injury. Weight, vision, health issues, etc.
But, as a firefighter we definitely had pre-employment, heck we had to be physically fit to take the examination just to pass the physical agility test to be considered for an interview. And don't get me started on the military.

You will have an uphill battle with HR on this. It requires them to do a lot of work to ensure that any preemployment screening is related to the job requirements and that id does not create an adverse impact on protected groups. Drew mentions that fire departments and police departments do physical agility test. This is true. There is also a long history of litigation about these test. It has taken a lot of work for both these groups to develop physical ability test that are job related and do not discriminate. It wasn't until the fire service develop and began using the standardized candidate physical ability test that the lawsuits went away.

If you are talking about doing some type of medical screening, you can only do this after a job offer is made. These screenings also have a long history of legal challenges.

HR doesn't want to let you do this because of the amount of work it takes to the job performance studies and the time to develop and validate the testing process. They are afraid of ADA lawsuits related to these types of screenings.

I would say use an Occupational clinic designed for workers, they follow all the same HIPPA laws, I think you should be fine.