I've read recently about implanted and external micro-chips for ill patients and house arrest convicts which tracks by GPS. Technology is also on the verge of micro-processors that fit on the head of a pin. It appears the ability to locate a smart card via GPS is just around the corner. This is where I draw my line in the sand...I will never carry such an abomination.
Agree wholeheartly about the illegal alien situation.
What you're talking about is called "vaporware." Digital Angel has yet to ship one functional unit. Also, the effort required to precisely track down the target requires a LOT of manpower for one person. Solution? Get one of those mylay anti-static bags for shipping computer chips around and stick the card in it when you're not using it.