Who decides the proper line of action when team members disagree?

We had a heated argument in our team - between the PO and a team member. The PO desired that a team member should carry out a change in the business logic of a stored procedure, while the developer was not happy with this decision and refused to comply. The PO feels that the developer has no right to question the decision while the developer thinks the decision is inappropriate and should not be implemented. Regarding this issue, who should decide what should be done? Scrum supports collaboration so should the team decide unanimously? How can conflicting opinions be resolved?

Posted By - Member