class BlogsController < ApplicationController
  before_action :check_authorization
  ...

  private
  def check_authorization
    authorize :blog
  end
end

def check_authorization
    authorize @blog
  end

class SomeOtherBlogsController < ApplicationController
  before_action :check_authorization
  ...

  private
  def check_authorization
    authorize :some_other_blog, @blog
  end
end