In Bootstrap, this looks for a string in the URL and actives the tabs for either English or Spanish without having to open a different window.

ActiveTab_JQuery.js

$(document).ready(function () {
	if (window.location.href.indexOf("?lang=en") > -1) {
		function doEnglish() {
			$('#english').addClass('active');
			$('#en').addClass('active');
			$('#español').removeClass('active');
			$('#es').removeClass('active');
		}
		setTimeout(doEnglish, 0);
	} else {
		function doSpanish() {
			$('#español').addClass('active');
			$('#es').addClass('active');
			$('#english').removeClass('active');
			$('#en').removeClass('active');
		}
		setTimeout(doSpanish, 0);
	}
});