Possible solution for CanCan Issue #646?

gistfile1.rb

class CanCan::ModelAdapters::ActiveRecordAdapter

  def conditions

    if @rules.size == 1 && @rules.first.base_behavior
      # Return the conditions directly if there's just one definition
      dig(tableized_conditions(@rules.first.conditions).dup)
    else
      @rules.reverse.inject(false_sql) do |sql, rule|
        merge_conditions(sql, dig(tableized_conditions(rule.conditions).dup), rule.base_behavior)
      end
    end
  end

  #dig into the hash to get conditions
  def dig(hash, h = {}, pk = nil)
    hash.inject(h) do |h, (k,v)|
      if v.kind_of? Hash
        dig(v, h, k )
      else
        pk ? h[pk] = { k => v} : h[k]=v
        h
      end
    end
  end

end