Workaround to unbind the event listeners for the agreement checkboxes

gistfile1.js

<script type="text/javascript">
//<![CDATA[
// submit buttons are not needed when submitting with ajax
$('review_submit').hide();
if ($('update_shipping_method_submit')) {
    $('update_shipping_method_submit').hide();
}

<?php if ($this->getUseAjax()):?>
    OrderReviewController.prototype._submitOrder = function() {
        if (this._canSubmitOrder) {
            if (this._pleaseWait) {
                this._pleaseWait.show();
            }
            new Ajax.Request(this.form.action, {
                parameters: {isAjax: 1, method: 'POST'},
                onSuccess: function(transport) {
                    try{
                        response = eval('(' + transport.responseText + ')');
                    } catch (e) {
                        response = {};
                    }
                    if (response.redirect) {
                        setLocation(response.redirect);
                        return;
                    }
                    if (response.success) {
                        setLocation('<?php echo $this->getSuccessUrl()?>');
                        return;
                    } else {
                        var msg = response.error_messages;
                        if (typeof(msg)=='object') {
                            msg = msg.join("\n");
                        }
                        if (msg) {
                            $('review-please-wait').hide();
                            alert(msg);
                            return;
                        }
                    }
                    $('review-please-wait').hide();
                    alert('<?php echo $this->jsQuoteEscape($this->__('Unknown Error. Please try again later.')); ?>');
                    return;
                },
                onFailure: function(){
                    alert('<?php echo $this->jsQuoteEscape($this->__('Server Error. Please try again.')) ?>');
                    $('review-please-wait').hide();
                }
            });
        }
    }
<?php endif ?>
PayPalExpressAjax = new OrderReviewController($('order_review_form'), $('review_button'),
    'shipping_method', null, 'details-reload'
);
PayPalExpressAjax.addPleaseWait($('review-please-wait'));
PayPalExpressAjax.setShippingAddressContainer($('shipping-address'));
PayPalExpressAjax.setShippingMethodContainer('shipping-method-container');
PayPalExpressAjax.shippingMethodsUpdateUrl = '<?php echo $this->escapeHtml($this->getUpdateShippingMethodsUrl()) ?>';
PayPalExpressAjax.setUpdateButton($('update_order'),'<?php echo $this->escapeHtml($this->getUpdateOrderSubmitUrl()) ?>','details-reload');
if ($('billing:as_shipping')) {
    PayPalExpressAjax.setCopyElement($('billing:as_shipping'));
}

//Workaround to unbind the event listeners for the agreement checkboxes
var agreementsBlock = $$('.checkout-agreements p.agree')[0];
if(agreementsBlock != undefined) {
    agreementsBlock.replace('<p class="agree">' + agreementsBlock.innerHTML + '</p>');
}
//]]>
</script>

Thanks!! But if you have more than one checkboxes you can use:
https://gist.github.com/thorstenfriesen/5574702