Dictionary.com
definitions

guilt by association

The attribution of guilt to individuals because of the people or organizations with which they associate, rather than because of any crime that they have committed.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

Examples from the Web for guilt by association

Contemporary Examples of guilt by association