They show that the requirements of the law are written on their hearts, their consciences also bearing witness, and their thoughts now accusing, now even defending them.) (NIV)
They show that the essential requirements of the Law are written in their hearts and are operating there, with which their consciences (sense of right and wrong) also bear witness; and their [moral] decisions (their arguments of reason, their condemning or approving thoughts) will accuse or perhaps defend and excuse [them] (AMP)
Which shew the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;) (KJV)