This case states that a parent has never been charged with a crime committed by their child. As of the year 2015, many parents have now been held responsible, and legally charged, for crimes committed by their children.
"In Loco Parentis" is Latin for "in the place of a parent" and refers to the legal responsibility of either a person or organization when they take on the function or responsibilities of a parent. In common law term this has two meanings. First: It can allow colleges and schools to act in the best interests of their student and legally assume some of the responsibilities a parent would normally have, especially if a student is underage and is going to a distant school where the student won't be able to be supervised by a parent during non-school hours. Second: It can give non-biological parents or persons the legal rights and responsibilities of a biological parent in certain situations, though this is not the same thing as adoption, it just allows someone to act as a child's legal guardian in certain situations where the biological parent might not be fit for whatever reason. One way this can happen is when the court assigns a minor what is known as a "guardian ad litem", which is someone (usually someone from child protective services) who is given temporary power of attorney and legal guardianship over a minor in order to act in the minor's best interests, this is often done if the minor is involved in a criminal proceeding as either a victim or defendant. This is usually done in situations where a minor's parent is no longer a fit guardian, like in the cases of abuse, or if the minor's parents are dead and the minor has no other blood relatives who are able to act as a guardian.
Broadway star Robert Morse (from How to Succeed in Business Without Really Trying (1967)) has a brief cameo as a building supervisor. He utters a paraphrased line from the play and Detective Ed Green (Jesse L. Martin) utters the response line, also paraphrased.
Adam Schiff refers to and quotes Potter Stewart. Stewart was a US supreme court justice, apppointed by Eisenhower, who served from 1958-1981.
Law & Order: Special Victims Unit (1999) has a similarly-titled episode, "In Loco Parentis (2018)", in season 19.