Woops!! This is a re-write of post 16, because I have just realised that I got this commandment wrong.
The ninth commandment has an application in modern society, but it is not a law to be enforced across the entire community. The command is only relevant to the judicial process. It applies to judicial procedure and is not a general law.
You shall not give false testimony against your neighbour (Ex 20:16).Honesty and truth are essential for the working of the judicial system. Witnesses much not give false testimony, whether to protect themselves or to protect someone else. Judges must always follow the truth, no matter where it leads.
The Bible applies a reverse golden rule to those who give false evidence: having done to yourself what you were doing to others (Deut 19:16-19). The liar receives the penalty that they person they were lying about might have received.
So that actually leaves just two of the ten commandments as general laws to be enforced by the civil authorities in the modern world. I have corrected post 13 to reflect this change.