Design Patent opposition in USA may be post issuance or pre issuance opposition.
Any person who has doubts of similarity of a newly approved and registered design with his owned design patent or the used design, can file a petition of the reexamination with the USPTO challenging the validity of the grant of the design patent. this is called Post Grant Review and Re-Examinations or opposition of a granted design patent.
Pre-issuance submission by any one is also allowed in USA. Since 2012 a third party can anonymously submit patents, published patent applications and other documents during the examination of a pending US patent application.
Intellectual Property Logium assists for design patent opposition and its defence.