From Fan History Wiki
The term chan, in western fan fiction communities, dates to the Masters and Apprentice mailing list. In 1999, members of this Star Wars fan fiction list started using the term to mean any story featuring a sexual relationship between an adult and some one under the age of 18.
- Chan-slash - Sexual interaction between two characters where one is significantly younger than the other. Also sometimes refers to relationships where one character has a dominant, mentoring "teacher" role, regardless of age difference (or lack thereof). 
- "Chan" is evidently shorthand for "chanslash" which means:
- Slash stories wherein one member of the pairing is under the legal age of consent (usually between 13-18 years of age but can also be under 21). When George Lucas based the Jedi upon Samurai warriors, he neglected the fact that the Samurai expected apprentices to "service" them in return for training. Many Phantom Menace slash writers have thus interpreted this into Jedi tradition. 
- Chan actually can be used for Male/Female sexual relationships. And some use it to mention two minors together (under 18) Most use it to label an adult character (over 18) with a much younger character. For instance Hermione being 12 and Severus being 31. Etc.
- Chan also roughly translates into "cute", "small child", "young". Urban dictionary states: "a japanese honorific, or suffix added to the end of one's name. chan is usually used when:
- 1. the person is a small child, ie, younger sibling or friends sibling
- 2. the person is cute, usually younger, usually a girl
- 3. can be used on pet cats, dogs, etc.." 
Below is a timeline of chan related events in fandom.
- In late February/ early March, 2005, God Awful Fan Fiction posters went after Pornish Pixies for a Harry Potter story by ailei which amounted to a "chan/slash/incest/twincest porn story" because God Awful Fan Fiction posters did not like that minors were able to readily access this story. 
- On August 3, 2007, LiveJournal suspended two pornish pixies members for posting images of a Harry Potter character who was a minor in a sexually explicit way. One piece of fan art featured an age-ambiguous Harry Potter--aged between 14 and 20--giving oral sex to Snape, his 40 year old teacher.
- In 2007, "there was a huge blow up on one of the HP chan mailing lists a few years ago, because the mod insisted on stripping the chan warnings from fics posted to the list because she said they weren't necessary. A lot of the writers got upset because the list's archive was available to the public, and people were linking to stuff that had no chan warnings on it so if you weren't aware of the content of the list you could stumble across something you weren't prepared for and might not want to read." 
This section needs more information.
- Osaka Considers Regulating Boys-Love Materials on AnimeNewsNetwork on April 4, 2010
- Osaka Considering Regulation of Female-Oriented Manga by Daniella Orihuela-Gruber on April 5, 2010
- Osaka Considering Regulating "Boy's Love" Manga by Brian Ashcraft on April 5, 2010
- Nonexistent children still refusing to exist in spite of more attempts to legislate their existence by fanficforensics on April 8, 2010
- Loli Around the World: A Look At Current Laws by gia manry on April 8, 2010