Block on Trump's Asylum Ban Upheld by Supreme Court
Today I learned that you could one day stab me in the back.
There's no doubt that writing about your problems, like talking about them, is therapeutic. However, you may want to think about drawing the line when it comes to confessing crimes to your diary.
While you don't have to worry about your diary calling the police to report you, if you are arrested and your diary is discovered during a valid search, it can be used against you as evidence in court. Also, as one teen recently learned, if you live with roommates, or family, there's likely to be no Fourth Amendment protection against your privacy being invaded if one of them reads your diary and reports you to law enforcement.
But I Thought My Diary Was Confidential
There are civil legal protections that permit a person to sue when another invades their privacy, or worse, discloses or publishes private information. However, the key term there is "civil." In the criminal justice system, if a person's diary was legally obtained during a search, and relevant to the charges, it is fair game to use against a criminal defendant. However, typically only the relevant entries will be admissible as evidence.
Fortunately, just because a person is arrested for a crime does not automatically entitle the police to read a diary. For example, if you are arrested for a simple drunk driving charge, the police are not going to be able to get a search warrant to go through your home, or diary, unless a search of the car turns up evidence of a more serious crime. However, if you are arrested for selling drugs, then a search of your home is likely, as it could potentially turn up evidence, and would entitle investigators to read your diary.
On the other hand, a diary can also be used to save a criminal defendant if certain entries help to prove their innocence. For example, if a prosecutor asks where a person was on July 29, the person can refer to their diary to refresh their recollection of being at home in bed, and as evidence to prove they were nowhere near the crime scene.