The Underdeveloped Planet Preservation Pact, UP3 for short, is a treaty aimed at protecting planets with civilizations that are not yet fully developed. Federation laws strictly prohibit contact with such planets and the reason for this is because contact with higher civilizations often greatly influences the path of history of underdeveloped worlds. All citizens and groups belonging to the Pangalactic Federation are required to adhere to this treaty, unless there is a clear and present danger to a person's life. This treaty is one of the most important sets of rules in the Pangalactic Federation, and delineates how citizens must act in emergency situations. Of course, in certain quarters, this treaty is thought to exist in name only.
Excerpt from the Star Ocean Wikia
The planets protected by the UP3
Planet Edifice
Planet Vanguard III
Planet Elicoor II
This means that if your character does not live on this planet. That you cannot casually visit this planet. If your character absolutely has to land on an underdeveloped planet. Then so be it. Please refrain from contacting or interacting with the local populace because you may or may not influence the timeline of that race. Needless to say, do not teach them how to build a phase gun.
There are some organizations that directly bypass the UP3 out of spite for the Pangalactic Federation. These organizations are the planets of Rezerb, Vendeen, and the planets of Quark. So if your character belongs to any of these people, you may directly come in contact with anything on these Undeveloped planets. Needless to say, the minute the Federation gets word of this, they will send an operative to extract you from the planet before too much damage is done. Although it is possible for a character to remain undetected in an underdeveloped planet for a long period of time, much like Norton the Rezerbian. Who spent five years on Vanguard III before Fayt found him when he crashlanded on the planet.