There are no employment regulations that would prevent an employer from hiring an employee below the published job requirements. The key is supporting the employment decisions that were made. Context is important, too. What were the surrounding circumstances, why did you change the criteria and job level, who were in the applicant pool, and who was not selected. If OFCCP or EEOC were to look into this, would you be able to show that there was no steering involved and no adverse treatment or disparate impact on more experienced and possibly older applicants or other applicants in a protected class? Employers are given a lot of latitude in making employment decisions to select the most suitable candidate. They just need to ensure that they have the proper documentation to support these decisions and withstand scrutiny. That said, just because you can, doesn’t mean it’s best practice, especially if your company is a federal contractor. Co-mingling applicant pools can create a much bigger applicant pool for that hire and bigger numbers are bad numbers for adverse impact analyses. As a best practice, it is better to repost the Junior Engineer position with the modified qualifications, and invite applicants to apply.