County Clerk is a civil servant job, and as such, anyone employed as a County Clerk is required to comply with the law. Kim Davis does not have the right in her capacity as a civil servant to decide which laws to enforce and which laws she can ignore. If Kim Davis is allowed to disobey the law, then anyone who decides a law is unjust - e.g., anti-drug laws - will be free to ignore any law he or she doesn't like. The result will be complete chaos and anarchy in our country.
If Kim Davis feels it is wrong to give marriage licenses to same sex couples, then she needs to resign from a job that requires her to do so. She is not free to ignore a valid - albeit immoral - law. St. Thomas More set the precedent for us, and we need to follow his example.