The ring typically reserves a small portion of their power for a passive force field that "protects the wielder from mortal harm".

She is also the one responsible for casting the spells on Balder to protect him from mortal harm.

I have an an aura about me that protects me from mortal harm.

She scrambled to her feet, already cursing, and he turned his full attention back to those who meant him mortal harm.

My greatest fear was they would do him mortal harm.

"Thus far, he lacks the occult knowledge to wreak intentional mortal harm upon you with his talismans."

Green Lantern rings typically reserve a small portion of their power for a passive force field that protects its wielder from mortal harm.

Then he went on harshly, "She committed a mortal harm against herself.

But he could not believe that the puny people who had been subject to his will for so long could possibly do him mortal harm.

Most everyone knew that Ben-Judah was "their guy," and thus he had so far eluded mortal harm.