Asked by user in Washington.
I’m sorry this happened to your son.
Unfortunately, your landlord is probably not liable for the injuries to your son. In Washington, a landlord has a duty to use “ordinary care” to protect against “foreseeable” criminal acts. In this case, the intentional tort was probably not foreseeable. Your landlord might be liable if, for example, the other tenant’s son repeatedly threatened your son and the landlord knew about the threats and didn’t take reasonable steps to prevent the incident from occurring.
On the other hand, the boy’s parents may be held liable for the boy’s intentional tort under Washington’s parental responsibility law (RCW 4.24.190). Under the law, the boy’s parents can be held liable for damages up to $5,000.