ITId = '{!User.IT_Lead__c}';
Support_Lead = '{!Case.Support_Lead__c}';
if(Support_Lead == null || Support_Lead == '')
{
if(ITId == true || DevId == true)
{
alert('A Support Lead must be present on the case before you can do work on this!');
}
else
{
alert('A Support Lead must be present on the case before you can do work on this!');
}
}