You can prevent a violation of your rights or rectify it during the criminal proceedings by submitting a complaint.
Complaint procedures
There are separate procedures for complaints during the pre-trial stage and then during the trial stage. If you have not used them, you won’t be able to subsequently complain to the international human rights institutions.
Compensation
If you have complained but a violation of your rights was not been rectified during the national trial proceedings, you may later apply to the international human rights institutions to establish whether your right to a fair trial has been violated and to obtain compensation.