In field hockey, a goal can only be scored if the ball is played by an attacker inside the circle, then crosses the goal-line under the crossbar without leaving the circle in between.
This applies even if a defender has touched the ball prior to the attacker, or touches the ball between the attacker and the goal. If the attacker would not have scored without the defender's action, the latter is sometimes informally called an own goal. However, the last attacker to touch the ball inside the circle is typically given credit, due to the rule requiring the attacker's touch.
If the ball is not played by an attacker inside the circle, a goal simply cannot be scored. Should only a defender touch it instead, no goal is given, and play restarts with a (long) corner as with any other instance of the ball leaving play over the back-line.
The FIH previously included a mandatory experimental rule which provided for scoring own goals - a defender's touch inside the circle also counted for scoring a goal if the ball entered the goal. However it was widely disliked and did not serve to improve the game as hoped, so the rule was reverted to its previous form.