These contentions misapprehend the reliability needed for a tip to justify a Terry stop. Such a tip, however, does not show that the tipster has knowledge of concealed criminal activity. The reasonable suspicion here at issue requires that a tip be reliable in its assertion of illegality, not just in its tendency to identify a determinate person. Under such an exception, a tip alleging an illegal gun would justify a stop and frisk even if the accusation would fail standard pre-search reliability testing. We decline to adopt this position.
Firearms are dangerous, and extraordinary dangers sometimes justify unusual precautions.
But an automatic firearm exception to our established reliability analysis would rove too far. Such an exception would enable any person seeking to harass another to set in motion an intrusive, embarrassing police search of the targeted person simply by placing an anonymous call falsely reporting the target's unlawful carriage of a gun. Nor could one securely confine such an exception to allegations involving firearms. Several Courts of Appeals have held it per se foreseeable for people carrying significant amounts of illegal drugs to be carrying guns as well. As we clarified when we made indicia of reliability critical in Adams and White, the Fourth Amendment is not so easily satisfied.