I have not been an employer. But I have some experience to be involved in a job interview. I had to choose the new subordinate of mine among several applicants. A job interview is quite stressful, not only for the applicants but also for the interviewers.
To begin with, there are many taboos in the interview. You should not ask the candidates about anything unrelated to the job itself. In particular, questions about religions, ideologies, or others with a possibility to inflict some discrimination are strictly prohibited. For example, you should not ask the marriage status of the applicant.
According to the article below, you should not ask the amount of salary the applicant took in the former job. Referring the information of salary history in each employee can lead to fixation of the inequality of earning.
Sydney Morning Herald: The one question you shouldn't ask in a job interview
I think it is an interesting opinion. Indeed, we tend to judge a person based on his salary, rather than examining his own ability. Higher wages have a power of branding.
On the other hand, there are some applicants willing to disclose their salary in the past. They claim that they are worthy to get a higher pay. It is quite natural for the applicants to express their value as much as possible.
These principles are officially also committed in Japan. Ministry of Health, Labour and Welfare published a guideline about a job interview. However, the guideline is hardly adhered in Japan, as far as I know. The interviewers frequently ask familial status to the applicants. They are afraid of women to quit the job when they get pregnant. It is another problem that pregnant women have great difficulty in continuing the work in Japan. Anyway, gender discrimination is common in Japanese companies, to be shameful.
My past entry: Japan as the worst for women
Recently, CV attached with a face photograph of the applicant became rare, perhaps to avoid inflicting prejudice, especially in the race. In Japan, however, everyone take a photo to attach it to the CV. Surprisingly, there is a rumor that some interviewers accept only the handwritten CV. They say that CV created using a word processor is not trustworthy because they are easy to duplicate. Considering this, most applicants submit handwritten CV. Ridiculous!
I think that the situation of job interview in Japan is outdated. However, I am not sure what kind of job interview is the best way to select the fittest person in the fair method. Recently, Google withdrew the brain teaser as a procedure of job interview. It may require more time to clarify whether the new standard of Google is effective.
My past entry: New standard of adoption in Google
My past entry: Hiring interview for Google and me
In my opinion, there is no better way to assess the candidates than relying on your impression, in the presence. Some workers have good talents but the difficulty in cooperating with others. I know that some of my subordinates made a great progress in the work after a few years in spite of their poor performance at the time of recruitment. The human spirit is complex and unpredictable.