During the loyalty mission Tali: Treason, you will have to decide whether to present the evidence against her father or not.
Choice: Present the Evidence or Don’t Present the Evidence
During the mission Tali: Treason, after ther Geth Prime fight, you’ll get some evidence incriminating Tali’s father, Admiral Rael’Zorah, of reactivating the Geth, and linking them up in neural networks to reach sapience, so he can perform weapon tests on them. Admiral Rael’Zorah will tell you that Tali had no knowledge of his crimes, and Tali will beg you not to show the evidence at trial to preserve her fathers name. After arriving at the Rayya, the admirals will ask you if you discovered anything at Alarei, Tali will plead to you once more, and you’ll have some very important choices to make.
Choice: Present the Evidence
If you present the evidence of Admiral Rael’Zorah’s crimes, you’ll gain thirty Renegade points, and Tali will be declared innocent. Admiral Rael’Zorah will be exiled, and have his name wiped of every ship he’s ever served. The Migrant Fleet will become Balkanized, and the data from her fathers tests will bring a lot of tension, with some ships wanting the data to make weapons against the Geth, and others, wanting to make peace with them. On top of all that, Tali will become disloyal to you which will affect her/and others chances of survival during the Suicide Mission. Finally, if she still survives after it, you won’t be able to have a peaceful resolution with the Geth/Quarian storyline in Mass Effect 3.
Choice: Don’t Present the Evidence
If you don’t present the evidence of Admiral Rael’Zorah’s crimes, you’ll gain thirty Paragon points, but Tali will be convicted for Treason, and get punished by exile of the Migrant Fleet. Surprising, you’ll get Tali’s loyalty, but you won’t be able to have a peaceful resolution with the Geth/Quarian storyline in Mass Effect 3.
Choice: Charm or Intimidate
You’ll be able to Charm the admiral by choosing the “I don’t need evidence” option, you’ll gain 30 Paragon points, and the board will exonerate Tali, giving you her loyalty. If you Intimidate the admiral by choosing the “You’re wasting our time!” option, you’ll gain 30 Renegade points, also exonerating Tali, giving you her loyalty.
Since you did this without presenting the evidence against her father, you’ll have a better chance of peaceful resolution in the Geth/Quarian storyline in Mass Effect 3.
Choice: Rally the Crowd
If you spoke to the Admirals before the trial, Veetor, and Kal’Reegar will be present amongst the Admirals, and you’ll be able to rally the crowd, resulting in Veetor, and Kal’Reegar speaking on her behalf, saying that Tali has done more for the fleet than the Admirals ever will. You’ll gain 30 Paragon points, and Tali’s loyalty. This option will only be available if Veetor was returned to the Fleet instead of Cerberus during the Freedom’s Progress mission at the beginning of the game, and Kal’Reegar survived Haestrom.