As a Starfinder Society GM, you have the right and responsibility to make whatever judgments, within the rules, that you feel are necessary at your table to ensure everyone has a fair and fun experience.

This does not mean you can contradict rules or restrictions outlined in this document (including the requirement to Run As Written), a published Starfinder RPG source, errata document (like the Starfinder FAQ and Errata), or official FAQ (like the Starfinder Society FAQ) on paizo.com. What it does mean is that only you can judge what is right for your table for cases that are not covered in those sources.
Some examples of GM discretion include the following:

• Creature tactics that have been invalidated by the players' actions.
• Situations or player actions not covered by the rules.
• Unclear rules.
• Terrain or environmental conditions described by the scenario, but not given mechanics.
  • However, if mechanics are included, they cannot be altered.
• Reactions of NPCs to good roleplaying, and the effect that has on the outcome of the encounter. Alternate or creative skills used to bypass or overcome traps and skill checks.
  • Note that DCs and results of the check are part of the mechanics and cannot be changed.
• Aspects of the scenario’s description and story as appropriate for the players at the table as described in the section "Running the Game" (Starfinder Core Rulebook 392).
• Changes required to comply with the Acceptable Content provision of the Community Standards and Expectations.
• Creative solutions presented by players to overcome obstacles.
• Moving plot points missed by players to encounterable areas.
  • This does not include moving missed treasure.

If a particular issue comes up repeatedly or causes a significant problem in one of your games, please raise any questions or concerns on the Organized Play forums where Venture-Officers, members of Paizo’s Organized Play team, or fellow GMs can help you resolve it.

Errata and Adventures

If an errata or clarification changes how an ability works in a Scenario, follow the current rules. If that means that the ability no longer works with how NPC tactics are written, modify the tactics as best you can to incorporate the changes.

Death and GM Discretion

Given the dangers characters face once they become Starfinders, character death is a very real possibility (and a necessary one to maintain a sense of risk and danger in the game). However, GMs are asked to consider the player's experience when deciding whether to use especially lethal tactics or target a character in extreme danger of death, especially when the player is new to the game.