The Supreme Court agreed Friday to step into an environmental dispute over a gold-mining operation near Juneau, Alaska, and a California criminal case in which a convicted killer was granted a new trial.

The decisions to hear the cases were among the last actions by the Supreme Court before its lengthy summer break. The term that began in October featured major rulings striking down the handgun ban in the District of Columbia, slashing by 80 percent a punitive damages award for victims of the Exxon Valdez oil spill and granting prisoners at Guantanamo Bay access to U.S. civilian courts.