diff --git a/system/language/english/form_validation_lang.php b/system/language/english/form_validation_lang.php
index 3f24090..abc30bc 100644
--- a/system/language/english/form_validation_lang.php
+++ b/system/language/english/form_validation_lang.php
@@ -1,4 +1,4 @@
-<?php
+	<?php
 
 $lang['required']			= "The %s field is required.";
 $lang['isset']				= "The %s field must have a value.";
@@ -17,6 +17,7 @@
 $lang['integer']			= "The %s field must contain an integer.";
 $lang['regex_match']		= "The %s field is not in the correct format.";
 $lang['matches']			= "The %s field does not match the %s field.";
+$lang['is_unique'] 			= "The %s field must contain a unique value.";
 $lang['is_natural']			= "The %s field must contain only positive numbers.";
 $lang['is_natural_no_zero']	= "The %s field must contain a number greater than zero.";
 $lang['decimal']			= "The %s field must contain a decimal number.";
diff --git a/system/libraries/Form_validation.php b/system/libraries/Form_validation.php
index d8bcbd6..c71c8b5 100644
--- a/system/libraries/Form_validation.php
+++ b/system/libraries/Form_validation.php
@@ -26,16 +26,15 @@
  */
 class CI_Form_validation {
 
-	var $CI;
-	var $_field_data			= array();
-	var $_config_rules			= array();
-	var $_error_array			= array();
-	var $_error_messages		= array();
-	var $_error_prefix			= '<p>';
-	var $_error_suffix			= '</p>';
-	var $error_string			= '';
-	var $_safe_form_data		= FALSE;
-
+	protected $CI;
+	protected $_field_data			= array();
+	protected $_config_rules		= array();
+	protected $_error_array			= array();
+	protected $_error_messages		= array();
+	protected $_error_prefix		= '<p>';
+	protected $_error_suffix		= '</p>';
+	protected $error_string			= '';
+	protected $_safe_form_data		= FALSE;
 
 	/**
 	 * Constructor
@@ -72,7 +71,7 @@
 	 * @param	string
 	 * @return	void
 	 */
-	function set_rules($field, $label = '', $rules = '')
+	public function set_rules($field, $label = '', $rules = '')
 	{
 		// No reason to set rules if we have no POST data
 		if (count($_POST) == 0)
@@ -163,7 +162,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function set_message($lang, $val = '')
+	public function set_message($lang, $val = '')
 	{
 		if ( ! is_array($lang))
 		{
@@ -187,7 +186,7 @@
 	 * @param	string
 	 * @return	void
 	 */
-	function set_error_delimiters($prefix = '<p>', $suffix = '</p>')
+	public function set_error_delimiters($prefix = '<p>', $suffix = '</p>')
 	{
 		$this->_error_prefix = $prefix;
 		$this->_error_suffix = $suffix;
@@ -206,7 +205,7 @@
 	 * @param	string	the field name
 	 * @return	void
 	 */
-	function error($field = '', $prefix = '', $suffix = '')
+	public function error($field = '', $prefix = '', $suffix = '')
 	{
 		if ( ! isset($this->_field_data[$field]['error']) OR $this->_field_data[$field]['error'] == '')
 		{
@@ -238,7 +237,7 @@
 	 * @param	string
 	 * @return	str
 	 */
-	function error_string($prefix = '', $suffix = '')
+	public function error_string($prefix = '', $suffix = '')
 	{
 		// No errrors, validation passes!
 		if (count($this->_error_array) === 0)
@@ -279,7 +278,7 @@
 	 * @access	public
 	 * @return	bool
 	 */
-	function run($group = '')
+	public function run($group = '')
 	{
 		// Do we even have any data to process? Mm?
 		if (count($_POST) == 0)
@@ -374,7 +373,7 @@
 	 * @param	integer
 	 * @return	mixed
 	 */
-	function _reduce_array($array, $keys, $i = 0)
+	protected function _reduce_array($array, $keys, $i = 0)
 	{
 		if (is_array($array))
 		{
@@ -406,7 +405,7 @@
 	 * @access	private
 	 * @return	null
 	 */
-	function _reset_post_array()
+	protected function _reset_post_array()
 	{
 		foreach ($this->_field_data as $field => $row)
 		{
@@ -468,7 +467,7 @@
 	 * @param	integer
 	 * @return	mixed
 	 */
-	function _execute($row, $rules, $postdata = NULL, $cycles = 0)
+	protected function _execute($row, $rules, $postdata = NULL, $cycles = 0)
 	{
 		// If the $_POST data is an array we will run a recursive call
 		if (is_array($postdata))
@@ -695,7 +694,7 @@
 	 * @param	string	the field name
 	 * @return	string
 	 */
-	function _translate_fieldname($fieldname)
+	protected function _translate_fieldname($fieldname)
 	{
 		// Do we need to translate the field name?
 		// We look for the prefix lang: to determine this
@@ -727,7 +726,7 @@
 	 * @param	string
 	 * @return	void
 	 */
-	function set_value($field = '', $default = '')
+	public function set_value($field = '', $default = '')
 	{
 		if ( ! isset($this->_field_data[$field]))
 		{
@@ -757,7 +756,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function set_select($field = '', $value = '', $default = FALSE)
+	public function set_select($field = '', $value = '', $default = FALSE)
 	{
 		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
 		{
@@ -801,7 +800,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function set_radio($field = '', $value = '', $default = FALSE)
+	public function set_radio($field = '', $value = '', $default = FALSE)
 	{
 		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
 		{
@@ -845,7 +844,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function set_checkbox($field = '', $value = '', $default = FALSE)
+	public function set_checkbox($field = '', $value = '', $default = FALSE)
 	{
 		if ( ! isset($this->_field_data[$field]) OR ! isset($this->_field_data[$field]['postdata']))
 		{
@@ -885,7 +884,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function required($str)
+	public function required($str)
 	{
 		if ( ! is_array($str))
 		{
@@ -907,7 +906,7 @@
 	 * @param	regex
 	 * @return	bool
 	 */
-	function regex_match($str, $regex)
+	public function regex_match($str, $regex)
 	{
 		if ( ! preg_match($regex, $str))
 		{
@@ -927,7 +926,7 @@
 	 * @param	field
 	 * @return	bool
 	 */
-	function matches($str, $field)
+	public function matches($str, $field)
 	{
 		if ( ! isset($_POST[$field]))
 		{
@@ -938,6 +937,24 @@
 
 		return ($str !== $field) ? FALSE : TRUE;
 	}
+	
+	// --------------------------------------------------------------------
+
+	/**
+	 * Match one field to another
+	 *
+	 * @access	public
+	 * @param	string
+	 * @param	field
+	 * @return	bool
+	 */
+	public function is_unique($str, $field)
+	{
+		list($table, $field)=explode('.', $field);
+		$query = $this->CI->db->limit(1)->get_where($table, array($field => $str));
+		
+		return $query->num_rows() === 0;
+    }
 
 	// --------------------------------------------------------------------
 
@@ -949,7 +966,7 @@
 	 * @param	value
 	 * @return	bool
 	 */
-	function min_length($str, $val)
+	public function min_length($str, $val)
 	{
 		if (preg_match("/[^0-9]/", $val))
 		{
@@ -974,7 +991,7 @@
 	 * @param	value
 	 * @return	bool
 	 */
-	function max_length($str, $val)
+	public function max_length($str, $val)
 	{
 		if (preg_match("/[^0-9]/", $val))
 		{
@@ -999,7 +1016,7 @@
 	 * @param	value
 	 * @return	bool
 	 */
-	function exact_length($str, $val)
+	public function exact_length($str, $val)
 	{
 		if (preg_match("/[^0-9]/", $val))
 		{
@@ -1023,7 +1040,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function valid_email($str)
+	public function valid_email($str)
 	{
 		return ( ! preg_match("/^([a-z0-9\+_\-]+)(\.[a-z0-9\+_\-]+)*@([a-z0-9\-]+\.)+[a-z]{2,6}$/ix", $str)) ? FALSE : TRUE;
 	}
@@ -1037,7 +1054,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function valid_emails($str)
+	public function valid_emails($str)
 	{
 		if (strpos($str, ',') === FALSE)
 		{
@@ -1064,7 +1081,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function valid_ip($ip)
+	public function valid_ip($ip)
 	{
 		return $this->CI->input->valid_ip($ip);
 	}
@@ -1078,7 +1095,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function alpha($str)
+	public function alpha($str)
 	{
 		return ( ! preg_match("/^([a-z])+$/i", $str)) ? FALSE : TRUE;
 	}
@@ -1092,7 +1109,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function alpha_numeric($str)
+	public function alpha_numeric($str)
 	{
 		return ( ! preg_match("/^([a-z0-9])+$/i", $str)) ? FALSE : TRUE;
 	}
@@ -1106,7 +1123,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function alpha_dash($str)
+	public function alpha_dash($str)
 	{
 		return ( ! preg_match("/^([-a-z0-9_-])+$/i", $str)) ? FALSE : TRUE;
 	}
@@ -1120,7 +1137,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function numeric($str)
+	public function numeric($str)
 	{
 		return (bool)preg_match( '/^[\-+]?[0-9]*\.?[0-9]+$/', $str);
 
@@ -1135,7 +1152,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function is_numeric($str)
+	public function is_numeric($str)
 	{
 		return ( ! is_numeric($str)) ? FALSE : TRUE;
 	}
@@ -1149,7 +1166,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function integer($str)
+	public function integer($str)
 	{
 		return (bool) preg_match('/^[\-+]?[0-9]+$/', $str);
 	}
@@ -1163,7 +1180,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function decimal($str)
+	public function decimal($str)
 	{
 		return (bool) preg_match('/^[\-+]?[0-9]+\.[0-9]+$/', $str);
 	}
@@ -1177,7 +1194,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function greater_than($str, $min)
+	public function greater_than($str, $min)
 	{
 		if ( ! is_numeric($str))
 		{
@@ -1195,7 +1212,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function less_than($str, $max)
+	public function less_than($str, $max)
 	{
 		if ( ! is_numeric($str))
 		{
@@ -1213,7 +1230,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function is_natural($str)
+	public function is_natural($str)
 	{
 		return (bool) preg_match( '/^[0-9]+$/', $str);
 	}
@@ -1227,7 +1244,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function is_natural_no_zero($str)
+	public function is_natural_no_zero($str)
 	{
 		if ( ! preg_match( '/^[0-9]+$/', $str))
 		{
@@ -1254,7 +1271,7 @@
 	 * @param	string
 	 * @return	bool
 	 */
-	function valid_base64($str)
+	public function valid_base64($str)
 	{
 		return (bool) ! preg_match('/[^a-zA-Z0-9\/\+=]/', $str);
 	}
@@ -1271,7 +1288,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function prep_for_form($data = '')
+	public function prep_for_form($data = '')
 	{
 		if (is_array($data))
 		{
@@ -1300,7 +1317,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function prep_url($str = '')
+	public function prep_url($str = '')
 	{
 		if ($str == 'http://' OR $str == '')
 		{
@@ -1324,7 +1341,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function strip_image_tags($str)
+	public function strip_image_tags($str)
 	{
 		return $this->CI->input->strip_image_tags($str);
 	}
@@ -1338,7 +1355,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function xss_clean($str)
+	public function xss_clean($str)
 	{
 		return $this->CI->security->xss_clean($str);
 	}
@@ -1352,7 +1369,7 @@
 	 * @param	string
 	 * @return	string
 	 */
-	function encode_php_tags($str)
+	public function encode_php_tags($str)
 	{
 		return str_replace(array('<?php', '<?PHP', '<?', '?>'), array('&lt;?php', '&lt;?PHP', '&lt;?', '?&gt;'), $str);
 	}
@@ -1361,4 +1378,4 @@
 // END Form Validation Class
 
 /* End of file Form_validation.php */
-/* Location: ./system/libraries/Form_validation.php */
+/* Location: ./system/libraries/Form_validation.php */
\ No newline at end of file
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index 945fafb..ff89a9a 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -73,7 +73,7 @@
 			<li>Added Session Class userdata to the output profiler. Additionally, added a show/hide toggle on HTTP Headers, Session Data and Config Variables.</li>
 			<li>Removed internal usage of the <samp>EXT</samp> constant.</li>
 			<li>Visual updates to the welcome_message view file and default error templates. Thanks to <a href="https://bitbucket.org/danijelb">danijelb</a> for the pull request.</li>
-			<li>Added <samp>insert_batch()</samp> function to the PostgreSQL database driver.  Thanks to epallerols for the patch.</li>
+			<li>Added <samp>insert_batch()</samp> function to the PostgreSQL database driver. Thanks to epallerols for the patch.</li>
 
 		</ul>
 	</li>
@@ -85,6 +85,7 @@
 	<li>Libraries
 		<ul>
 			<li>Altered Session to use a longer match against the user_agent string. See upgrade notes if using database sessions.</li>
+			<li class="reactor">Added <kbd>is_unique</kbd> to the <a href="libraries/form_validation.html">Form Validation library</a>.</li>
 		</ul>
 	</li>
 </ul>
diff --git a/user_guide/libraries/form_validation.html b/user_guide/libraries/form_validation.html
index 54908d4..e68765c 100644
--- a/user_guide/libraries/form_validation.html
+++ b/user_guide/libraries/form_validation.html
@@ -390,10 +390,10 @@
 <p>CodeIgniter lets you pipe multiple rules together. Let's try it. Change your rules in the third parameter of rule setting function, like this:</p>
 
 <code>
-$this->form_validation->set_rules('username', 'Username', 'required|min_length[5]|max_length[12]');<br />
+$this->form_validation->set_rules('username', 'Username', 'required|min_length[5]|max_length[12]|is_unique[users.username]');<br />
 $this->form_validation->set_rules('password', 'Password', 'required|matches[passconf]');<br />
 $this->form_validation->set_rules('passconf', 'Password Confirmation', 'required');<br />
-$this->form_validation->set_rules('email', 'Email', 'required|valid_email');<br />
+$this->form_validation->set_rules('email', 'Email', 'required|valid_email|is_unique[users.email]');<br />
 </code>
 
 <p>The above code sets the following rules:</p>
@@ -516,7 +516,7 @@
 
 class Form extends CI_Controller {
 
-	function index()
+	public function index()
 	{
 		$this->load->helper(array('form', 'url'));
 
@@ -525,7 +525,7 @@
 		$this->form_validation->set_rules('username', 'Username', 'callback_username_check');
 		$this->form_validation->set_rules('password', 'Password', 'required');
 		$this->form_validation->set_rules('passconf', 'Password Confirmation', 'required');
-		$this->form_validation->set_rules('email', 'Email', 'required');
+		$this->form_validation->set_rules('email', 'Email', 'required|is_unique[users.email]');
 
 		if ($this->form_validation->run() == FALSE)
 		{
@@ -537,7 +537,7 @@
 		}
 	}
 
-	function username_check($str)
+	public function username_check($str)
 	{
 		if ($str == 'test')
 		{
@@ -947,6 +947,13 @@
 	</tr>
 
 	<tr>
+		<td class="td"><strong>is_unique</strong></td>
+		<td class="td">Yes</td>
+		<td class="td">Returns FALSE if the form element is not unique to the table and field name in the parameter.</td>
+		<td class="td">is_unique[table.field]</td>
+	</tr>
+
+	<tr>
 		<td class="td"><strong>min_length</strong></td>
 		<td class="td">Yes</td>
 		<td class="td">Returns FALSE if the form element is shorter then the parameter value.</td>