Normally, a bounty is issued by a Government official or by the Marines. The idea is to tempt others into aiding the capture of the criminal so they can be brought to justice quickly.

A bounty reflects both the threat and power of an individual. Engaging in activities deemed criminal by the World Government or associating with groups which engage in them is enough to warrant significant bounties, even if the criminal is not powerful themselves. In particular, direct opposition to the World Government, no matter the reason, is treated as a serious offense, and bounties are issued accordingly.

After a bounty is issued, it can later be increased for several reasons:
1-The threat of a person’s observed combat abilities.
2-More experienced bounty hunters volunteering to capture the individual or group.
3-Further criminal acts beyond the initial one.
4-Inspiring criminal acts when provoked or inciting others to act ‘criminally’.
5-Having knowledge deemed illegal by the World Government.
6-Solely being associated with a notable criminal figure.
Here are the 50 Highest Known Bounties ever in One Piece:
Gol D. Roger ฿5,564,800,000

Edward Newgate ฿5,046,000,000

Kaido ฿4,611,100,000

Charlotte Linlin ฿4,388,000,000

Shanks฿4,048,900,000

Marshall D. Teach ฿3,996,000,000

Dracule Mihawk ฿3,590,000,000

Buggy ฿3,189,000,000

Monkey D. Luffy ฿3,000,000,000

Trafalgar Law ฿3,000,000,000

Eustass Kid ฿3,000,000,000

Crocodile ฿1,965,000,000

King The Wildfire ฿1,390,000,000

Marco ฿1,374,000,000

Queen ฿1,320,000,000

Zoro ฿1,101,000,000

Jinbe ฿1,100,000,000

Charlotte Katakuri ฿1,057,000,000

Sanji ฿1,032,000,000

Jack ฿1,000,000,000

Charlotte Smoothie ฿932,000,000

Nico Robin ฿930,000,000

Charlotte Cracker ฿860,000,000

Charlotte Perospero ฿700,000,000

Sabo ฿602,000,000

Charlotte Snack ฿600,000,000

Who’s-Who ฿546,000,000

Little Oars Jr. ฿550,000,000

Portgas D. Ace ฿550,000,000

Chinjao ฿542,000,000

Izou ฿510,000,000

Usopp ฿500,000,000

Black Maria ฿480,000,000

Edward Weevil ฿480,000,000

Sasaki ฿472,000,000

Belo Betty ฿457,000,000

Tamago ฿429,000,000

Karasu ฿400,000,000

Ulti ฿400,000,000

Franky ฿394,000,000

Brook ฿383,000,000

Pedro ฿382,000,000

Nami ฿366,000,000

Capone Bege ฿350,000,000

Scratchmen Apoo ฿350,000,000

Donquixote Doflamingo ฿340,000,000

Cavendish ฿330,000,000

Pekoms ฿330,000,000

Basil Hawkins ฿320,000,000

Gecko Moria ฿320,000,000
