In theory if someone knew they were subject to data being collected about them they could bring a law-suit against the companies involved for breaching data pro

In theory if someone knew they were subject to data being collected about them they could bring a law-suit against the companies involved for breaching data protection and privacy legislation. The immunity that companies get from co-operating with the US government only covers them in the US, not in other countries. But in practice the only time people know this information is being collected on them is when a company (i.e Twitter) refuses to comply with such an order.