Why wasn't Shayera Hol arrested?!

From Justice League No. 16 (March 2019)

After the events of Justice League No. 14-16, some fans have wondered why Shayera Hol, the current ruler of Thanagar Prime, was not arrested by the Green Lantern Corps and was allowed to continue her rule. In the Justice League issues, we were introduced to a Shayera Hol who had moved her people from the destroyed Thanagar to Thanagar Prime.

 

From Justice League No. 14 (February 2019)

This was where the Thanagarians had originated from many years ago. Shayera captured the Martian Keep and rebuilt Thanagar with the powers of the Martian Keep and the Absorbascon.

From Justice League No. 14 (February 2019)

When Kendra Saunders, the Martian Manhunter and John Stewart came to investigate, they discovered the truth. Shayera attempted to kill them. She even called on a creature that appeared to be the Savage Hawkman, but it was just a copy created by the Absorbascon.

 

From Justice League No. 14 (February 2019)

Towards the end of the story, the Martian Keep died and Shayera lost control of the powers of the Absorbascon. The Savage Hawkman faded away, the grandeur of Thanagar crumbled away and the true Thanagar was revealed. Shayera almost killed herself in attempting to use the Absorbascon herself before she was stopped by the Martian Manhunter.

From Justice League No. 16 (March 2019)

The Green Lantern Corps arrived and attempted to arrest Shayera but Kendra began to intervene when Superman, Batman, Wonder Woman arrived with Starman.

From Justice League No. 16 (March 2019)

Starman used his powers to help Kendra and Shayera. He first explained that when Shiera died, she was split into two beings when she reincarnated. This was done by Perpetua to keep Kendra from having the full power of the Totality.
Starman made Kendra whole, unleashing her full potential and abilities to stop Perpetua. Kendra reached her full power and understood what she had to do for the first time. We're seeing that currently in the JL series. When Kendra was made whole, Shayera asked, "Did you just rip out my soul and give it to her?"
Starman replied, "Your soul is your own. Your story is your own, and I've given that back to you." In other words, Kendra became the being that Perpetua feared most, and Shayera became the one had the connection to Hawkman since the beginning of time.

From Justice League No. 16 (March 2019)

Shayera's heart and soul were set right and made whole. She made a complete 180 after that. She told Kendra what she had refused to tell her before. She vowed to rebuild Thanagar Prime in the right way. Because of what had happened, the GL Corps dropped the charges and decided to give Shayera a chance to help her people rebuild Thanagar.

Since she was made whole, she has helped the Justice League a few times in battles since then. She has led her fleet into battle against Lex Luthor and Perpetua. And now we see that she started rediscovering her connection to Carter Hall.

Justice League Annual No. 1 (March 2019)

The Shade witnessed Carter Hall being overcome by the Sky Tyrant, and he knew that the only way to bring Carter back was to contact Shayera, so he contacted her through the JL, knowing what the Hawks meant to each other. Shayera arrived on Earth to help Carter fight the influence of the Sky Tyrant. It appears that she also does not remember a lot of her past, but she remembers enough to know that she has a connection to Carter. She knows Carter better than anybody. She remembers many of their past lives. During her fight, she talked about some of their past lives together. While Kendra Saunders appears to not feel or desire any connection with Carter Hall, Shayera seems to be the one who remembers their past, has feelings for Carter and has a desire to reconnect.

 

From Hawkman No. 19 (February 2020)

Shayera arrived on Earth but quickly realized Hawkman was not himself. During her battle with the Sky Tyrant, Shayera said, "Whoever turned you into this, they don't understand what makes you work. No matter what it takes, I'll find a way. I'll fix you." Shayera proceeded to completely own the Sky Tyrant in battle, finally impaling him with his own mace and causing him to flee. 

So that's why she wasn't arrested. To put it simply, she wasn't herself. Like Sky Tyrant has overcome Carter Hall now, she wasn't the same person who had reincarnated across time and space with Carter. Like Sky Tyrant now, she also did not have what made her work before she was made whole. When Starman "repaired" both Kendra and Shayera, it was obvious to both the Justice League and the Green Lantern Corps that Shayera was no longer the incomplete version before. She had her morality, sense of right and wrong, and her love for Hawkman restored.
Since she has been made whole, she remembers her past, and she knows Carter Hall/Hawkman better than anyone. Whether this leads to them getting back together remains to be seen, but we can say that Hawkwoman is back!

Hawkman No. 19 cover by Pat Olliffe, Tom Palmer and Jeremiah Skipper