How to test for Elevated Privilege

$currentPrincipal = New-Object System.Security.Principal.WindowsPrincipal([System.Security.Principal.WindowsIdentity]::GetCurrent())
$administratorsRole = [System.Security.Principal.WindowsBuiltInRole]::Administrator
if (!$currentPrincipal.IsInRole($administratorsRole)) {
    Throw "This script must be run in an elevated session."
}