Through a series of seven episodes, Law & Order: Legacies tells crime stories that are loosely connected and based around detective and attorney characters from the universe of the Law & Order TV show, in particular the original series and its spin-off Law & Order: Special Victims Unit. Players work alongside nine popular characters from the shows (not voiced by their original actors) in solving the cases from police work to conviction. In the investigation part, witnesses have to be interrogated, crime scenes searched, and evidence collected. The information and proof so gathered is then used to build a case in the trial part, where players have to make their case in court and raise objections against unjust actions of the defense attorneys. The final outcome, ranging from conviction to complete acquittal, depends on the choices the player has made during both of the phases.
The game is controlled by pointing and clicking the mouse (Windows/Mac) or direct interaction (iOS), and uses stylized character likenesses in three-dimensional environments.
The Windows and Mac versions launched with three episodes initially for the full season price and the additional four were added afterwards on a monthly basis. For the iPhone and iPad versions the first episode was launched for a fee, with the ability to buy the other six as a multipack through in-app purchase. In February 2012 however the model was changed for a limited time. The app was then available for free along with the first episode, and the others needed to be bought in-game.