A more thorough explanation:

The plain-touch doctrine is a principle in criminal procedure that allows a police officer to seize any illegal or incriminating item that they can immediately and clearly identify by touch during a legal pat-down search. This means that the officer can only seize the item by touching it, but not by manipulating it.

For example, if a police officer is conducting a pat-down search and feels a small baggie in a suspect's pocket, they may seize it if they can immediately identify it as containing illegal drugs by touch alone. However, if the officer needs to manipulate the baggie to confirm its contents, they cannot seize it under the plain-touch doctrine.

The plain-touch doctrine is based on the idea that if an officer can immediately identify an item as illegal or incriminating by touch, it is reasonable to assume that the item would have been discovered during a more thorough search.