Interesting hiring rules of the U.S.

Suppose you work for a HR department and need to select a person for a certain position from candidates.

For instance, in general, you would have somewhat bias about candidates even if you don't think so or you are trained so.  "Contrast Error" is a term that evaluation is biased. For example, there are three different cups of water. The cup A has hot water inside. The cup B has room temperature water. The cup C has cold water. If you put your hand in the cup A, and then put it in the cup B, you would feel the cup B is warm. On the other hand, if you put your hand in the cup C first, and then put it in the cup B, you would feel the cup B is cold. Similar things occur in interviews because every person has somewhat certain biases.

Analyzing Graphology (Handwriting Analysis) is another interesting way that is used when HR people see candidates. I'm not sure if it practically useful or not.

Other typical questions about whether it is illegal in the U.S. ,when interviewer asked candidates, are following below.

"Do you have children?" ×

"Which country do your parents come from?" ×

"How old are you?" ×

"Have you ever been arrested?" -not illegal but-> useless or meaningless because even speeding is technically considered as being arrested.

"Do you own your own home?"  -not illegal but-> useless or meaningless

Since Japanese applications or resumes for job normally require face picture, age, marriage status, and sex, American style would be surprising Japanese people.