What legal case established that only a partial search is allowed when a citation is issued?

The case that established the principle that only a partial search is allowed when a citation is issued is Knowles v. Iowa. This case addressed the scope of vehicle searches during traffic stops. The Supreme Court ruled that when an officer issues a citation rather than making an arrest, the officer does not have the authority to conduct a full search of the vehicle. This ruling emphasized that the reasonableness of the search must be aligned with the justification for the stop. Since there was no arrest made in this situation, the court found that a full search was unwarranted and only a limited search could be conducted if there were specific grounds for concern about officer safety or evidence destruction. This case is significant as it clarifies the standards for searches associated with traffic citations, reinforcing the need for probable cause or reasonable suspicion to justify broader searches beyond what is necessary for the citation itself.