Application for trademark registration can be opposed if: 

• proprietary rights are violated,
• the mark is descriptive, non-distinctive, deceptive, misleading, disparaging, or causing confusion
• there is breach of copyright
• the mark is confusingly similar with an existing registered mark
• the mark uses any protected emblem or insignia
• rights to a business/company name or personal name are violated
• the word has broad or generic meaning
• there is violation in a registered design
• rights of a famous mark are violated
• the mark is indicative of a geographical location
• public policy or moral standards are violated