It doesn't need a warrant, and the requirements are varied. None of them require judicial review. * TARs and TANs both generally require that an agency be inve

It doesn't need a warrant, and the requirements are varied. None of them require judicial review. * TARs and TANs both generally require that an agency be investigating a serious crime (one that takes). There are some toy protections against abuse but they're basically meaningless (the AG or chief officer needs to be "satisfied" that it's reasonable and a few other token requirements -- need I remind you that we imprison refugees in sub-human conditions without the right to a trial, so "reasonable" is a stretch). * TCNs are even more general. They can be done purely "in the interests of national security".