Compulsory checkbox on login

Hello,

I have included a checkbox on login to make sure the user accepts the policy of our website before registering.

I need this action to be compulsory before proceeding to the registration.

How could I do this?

`<form name=”LoginWithAjax_Register” id=”LoginWithAjax_Register_Form” action=”<?php echo esc_url(home_url()); ?>/wp-login.php?action=register&callback=?&template=” method=”post”>
<p>
<label><input type=”text” placeholder=”Username” name=”user_login” id=”user_login” class=”input” size=”20″ tabindex=”10″ /></label>
</p>
<p>
<label><input type=”text” placeholder=”E-mail” name=”user_email” id=”user_email” class=”input” size=”25″ tabindex=”20″ /></label>
</p>
<?php do_action(‘register_form’); ?>
<p id=”reg_passmail”><?php esc_html_e(‘A password will be e-mailed to you.’, ‘fundingpress’) ?></p>
<br />
<input type=”checkbox”value=checked> He leído y acepto la <a href=”javascript:void(0);” onclick=”window.open(‘www.paramaparto/politica-de-privacidad’,’Privacidad’,’scrollbars=yes,width=400,height=400′)”><b><u>Polí­tica de privacidad</u></b></a>
<p class=”submit”><input type=”submit” name=”wp-submit” id=”wp-submit” class=”button-green button-small” value=”<?php esc_html_e(‘Register’, ‘fundingpress’); ?>” tabindex=”100″ /></p>
<input type=”hidden” name=”lwa” value=”1″ />
</form>`

So far, one can register whether or not the box is checked and the legal policy is approved.

Thanks in advance.