Suppose I have a Post model, and a Comment model. Using a common pattern, Post has_many Comments.
If Comment has a default_scope set:
default_scope w
Rails 4.1.1
Comment.unscope(where: :deleted_at) { Post.first.comments }
Or
Comment.unscoped { Post.first.comments.scope }
Note that I added .scope, it seems like this block should return kind of ActiveRecord_AssociationRelation (what .scope does) not ActiveRecord_Associations_CollectionProxy (without a .scope)