I know employees have rights once they are hired, but do I need to worry about any legal issues when recruiting? Can't I just hire who I like?

Well, yes and no. The full gamut of employment rights don't apply to external candidates for roles, but the Employment Equality Acts 1998 - 2015 do ("The Acts"). The Acts have a slightly misleading title as you don't always have to be in employment to rely on them. As many employers have discovered to their detriment over the years, the Acts apply equally to the recruitment process, because what good is a protection against discrimination if it only kicks in once someone is hired? The Acts apply equally to access to employment including the recruitment process in order to prevent someone's prejudice (knowingly or unknowingly) impeding someone else's opportunity to get their foot in the door