Deuteronomy 21 - When a murder takes place and no culprit is apprehended, the elders from the nearest town are to convene at the sight and make clear they knew nothing of the person responsible. They were to offer a sacrifice to clear the town of any guilt. Moses gives regulations regarding marriage to a foreign woman, how a firstborn child was to be treated, and how serious a rebellious child was to be judged. All these instructions were God's way of maintaining order in the community and to show how serious any disobedience was.
Deuteronomy 22 - Every Israelite was responsible to be fair to each other and to offer help when the need was apparent. If a man made an accusation against his new bride then her parents could give evidence that she was a virgin at the time of the wedding. If not, the girl would be executed. God also showed care for a young woman who becomes the victim of a serious attack.
Deuteronomy 23 - God has the right to regulate who may approach Him in worship. We know God especially pays attention to the condition of the heart. God wants His people to be clean in their hygiene and maintain a healthy environment. God also forbids the practice of making careless promises to Him. This is still a matter all believers today should be cautious to remember.