diff -rc activerecord-2.3.5.before/lib/active_record/validations.rb activerecord-2.3.5/lib/active_record/validations.rb
*** activerecord-2.3.5.before/lib/active_record/validations.rb	Fri Mar  4 14:38:15 2011
--- activerecord-2.3.5/lib/active_record/validations.rb	Fri Mar  4 14:50:45 2011
***************
*** 813,820 ****
            if scope = configuration[:scope]
              Array(scope).map do |scope_item|
                scope_value = record.send(scope_item)
!               condition_sql << " AND " << attribute_condition("#{record.class.quoted_table_name}.#{scope_item}", scope_value)
!               condition_params << scope_value
              end
            end
  
--- 813,838 ----
            if scope = configuration[:scope]
              Array(scope).map do |scope_item|
                scope_value = record.send(scope_item)
!               scope_column = finder_class.columns_hash[scope_item.to_s]
! 
!               if scope_value.nil?
!                 comparison_operator = "IS ?"
!               elsif scope_column.text?
!                 comparison_operator = "#{connection.case_sensitive_equality_operator} ?"
!                 scope_value = scope_column.limit ? scope_value.to_s.mb_chars[0, scope_column.limit] : scope_value.to_s
!               else
!                 comparison_operator = "= ?"
!               end
! 
!               sql_attribute = "#{record.class.quoted_table_name}.#{connection.quote_column_name(scope_item)}"
! 
!               if scope_value.nil? || (configuration[:case_sensitive] || !scope_column.text?)
!                 condition_sql << " AND " << "#{sql_attribute} #{comparison_operator}"
!                 condition_params << scope_value
!               else
!                 condition_sql << " AND " << "LOWER(#{sql_attribute}) #{comparison_operator}"
!                 condition_params << scope_value.mb_chars.downcase
!               end
              end
            end