Employers must pay their male and female employees who perform substantially similar work at wage rates that are the same
It is a combination of the following three elements, as required to perform the job, under similar working conditions:
experience, ability, education, and training
physical or mental exertion
Only if an employer can show that the wage difference results from one of the following "legitimate" reasons:
a system that measures production
a job-related factor other than sex that is consistent with a business necessity, such as education, training or experience.
It is the employer's obligation to establish one of these things, which is meant to be difficult, as the law is designed to get rid of the wage gap.
the degree of accountability or duties