Freedom of opinion and expression over the Internet are not a by-product of technical change or development, but a firm basis before this technique exists; this study has tried to talk about the crime committed because of breaking the boundaries of this freedom, namely the crimes of insult and slander as examples. Using a comparative analytical approach, the researcher tried to analyze the provisions of Omani law relating to the offences of online libel as examples of breaking the boundaries of freedom of opinion and expression, and ultimately concluded that the legal and regulatory environment for freedom of expression over the Internet was clearly provided for, and that the fundamental challenge in a democratic society was to find a reasonable balance between this freedom and other interests. Also, the offences of libel and slander are highly serious if committed online because of their ease and speed of spread and cross borders, which causes serious damage to the victim and is difficult to remedy. Finally, this study recommends spreading a culture of legal awareness about internet use, and individuals and internet pioneers should be aware of laws on the use of the Internet to protect themselves from criminalization.