Dhaka, Sept. 24 -- Popular tattoo artist Song Jaemin is booked weeks in advance and admired by clients from around the world. Yet each tattoo he inks is technically illegal, as South Korea only permits licensed doctors to perform the practice.

That could soon change. The National Assembly is expected to pass the Tattooist Act, a landmark bill that would allow non-medical professionals to legally give tattoos.

"I started this knowing it was illegal, but I believed the law would change one day," said Song, 28, at his studio near Seoul. "Many tattooists feel we're not doing anything wrong - it's just that there's no law for us."

For years, tens of thousands of tattoo artists have campaigned through rallies, court appeals, and petitions to...