No. Not even a non-sacramental confession to a random person is admissible in court. Or at least it would be difficult to prove. Someone has to witness you do the crime to be actually convicted.
I work in the justice system. Believe me, you can be convicted of a crime even if no one witnessed it. Very few serious crimes are actually witnessed. All the court has to do is find you guilty beyond a reasonable doubt. With thorough police investigations, and the advancement in technology for evidence collection, the courts are getting convictions for cold cases that sat for decades. Furthermore, someone could have witnessed you commit the crime, and you could still be found not guilty based on a technicality.
You’re so wrong on this, it’s actually sad. I have to be careful in my job that my clients who are on pre-trial don’t admit to me that they committed the crime. If they do, I am required to report it to my supervisor, the police, and the prosecutor, as well as go to court and testify to what they told me.
The whole, “You have the right to remain silent. Anything you say can and will be used against you in a court of law. You have the right to an attorney. If you cannot afford one, one will be provided to you a no cost. Do you understand your rights?” is based on the fact that someone’s confession to the police can be admitted as evidence into the court. Then the courts have to have a voir dire to determine whether or not that statement is admissible in court.
In Canada, there is no actual statute law that protects an individual’s confession of committing a crime to any priest, minister, etc. All that’s protecting you is what’s determined by case law, and the simple fact that on the priest’s end he’s not permitted to reveal any part of your confession to anyone even if he’s subpoenaed and would go to jail for obstruction of justice by refusing to testify.
Here’s the case law from the Supreme Court of Canada regarding admissibility of statements made to clergy members as evidence in court.
canlii.org/en/ca/scc/doc/1991/1991canlii40/1991canlii40.pdf