If DARPA really is behind the tools they are using, its sufficient GOVERNMENT ACTION to support the class action civil rights case under 42 U.S.C. 1983.
The exceptions are commonly grouped into two categories: ‘public function’ and ‘entanglement’ exceptions (Chemerinsky (2009) 552; Quint 267 et seq). Under the ‘public function’ exception, a private actor must be considered a state actor if it ‘performs the customary functions of government’ (Lloyd Corp Ltd v Tanner (1972) 562 (US)) or, more narrowly, if it performs a function that is ‘traditionally, exclusively reserved to the [s]tate’ (Barrows v Jackson (1953) 252 (US)). Examples include a private political party that determines the qualifications of eligible voters in its primary elections (Smith v Allwright (1944) 660 (US); Terry v Adams (1953) 481, 482 (US)), a private company that operates a town (Marsh v Alabama (1946) 508 (US)), or a private landowner who uses his land to operate a public park (Evans v Newton (1966) 302 (US)). Under the ‘entanglement’ exception, private action must be considered state action if the state ‘has so far insinuated itself into a position of interdependence’ with the private actor that ‘it must be recognized as a joint participant in the challenged activity’ (Burton v Wilmington Parking Authority (1961) 725 (US)) or, more generally, if the government has authorized, encouraged, or facilitated the private actor’s conduct (Chemerinsky (2009) 552). Examples include a state agency that is so strongly involved with the operation of a private restaurant (the agency owns the public building in which the restaurant is located, is responsible for the building’s maintenance, and receives rent from the restaurant, among others), that the private restaurant’s discrimination against African Americans must be considered state action (Burton v Wilmington Parking Authority (1961) 724, 725 (US)); a state that lends books to students of a racially segregated private school (Norwood v Harrison (1973) 466 (US)); or a court that enforces a private, racially restrictive covenant against a private party (Shelley v Kraemer (1948) 19 (US)) (racial discrimination).