Vulnerable witnesses now have the right to give evidence from behind a screen or by video link.
Evidence could be given by witnesses using a video link
The measures have been made available as part of the phased introduction of the 2004 Vulnerable Witnesses Act.
Witnesses with a mental disorder or who are in a state of fear, and whose evidence could be affected as a result, will be eligible for the extra support.
The Scottish Executive said all witnesses would now be able to play a full role in ensuring justice was done.
The protection improvements are aimed at witnesses involved in High Court and Sheriff Court jury cases, as well as Children's Hearings court proceedings.
Measures also include the use of a "supporter" who can sit beside the witness to help reassure them, and the use of a prior statement as the witness's main evidence.
In some non-sexual offence cases, a commissioner will be able to take evidence, meaning that evidence can be given out with the trial itself.
Deputy Justice Minister Hugh Henry said: "We are currently in the middle of the most radical programme of reforms to transform our criminal justice system in a generation.
"Central to those reforms is a determination to do all we can to ensure witnesses receive the support they need to enable them to provide the best possible evidence in court."