Logan's Loophole

"No one's going to put you out to pasture' cause you're going to stay young (and level 30) forever! You'll never again become addicted to chems, and they'll last twice as long... but after 30 you can kiss experience, perks, and skill points goodbye!"

- Fallout:New Vegas description

Logan's Loophole is a trait in the Fallout: New Vegas add-on Old World Blues.

Effect
Chems last twice as long and you never become addicted, but the level cap for your character is locked at 30, or your current level if higher than 30.

Behind the scenes

 * This trait is likely named after the post-apocalyptic dystopian book and film Logan's Run, in which a maximum age of 30 is enforced.