The principal responsibility of the IRB is to protect the rights, safety and welfare of human subjects.  The IRB determines if the benefits and knowledge to be gained outweigh the risks to which participants would be exposed.

IRBs operate according to policies within the Federal Drug Administration,
Department of Health and Human Services, Department of Justice, Office of
Research Integrity, Office for Human Research Protection, and the Office of Civil Rights.  Compliance with federal and state laws governing research ensures human participants have the highest level of protection, reducing risks to the lowest possible level.

If you are conducting a study that involves multiple sites, you may be required to obtain approval from more than one institution.