Victims of domestic abuse have been given more protection after a legal loophole was closed.
A new offence of engaging in threatening or abusive behaviour came into effect just after midnight.
It was introduced after a court ruling in July 2009 meant that the common law offence of breach of the peace was no longer appropriate in such abuse cases.
The 2009 ruling had required breach of the peace cases to have a "public" element.
The case meant many domestic abuse crimes could go unpunished because they were committed behind closed doors.
The new statutory offence, created through the recently-passed Criminal Justice and Licensing Act, does not require any public element for an offence to have been committed.
Justice Secretary Kenny MacAskill said: "This will give victims greater legal protection, whilst ensuring prosecutors have the full range of powers available to them to bring about a conviction.
"We want to send out the message loud and clear that if you carry out this offence, there will be no escape, there will be no wriggle room to exploit, and you will be met with the full force of law."
The new law states that it is an offence for a person to behave in a threatening or abusive manner where the behaviour would be likely to cause a reasonable person to suffer from fear or alarm.