Ethics related to the practices or controversies surrounding scanlation, from the scanlation of licensed series to the standards and courtesy applied to scanlations of doujinshi, to practices such as scanlation poaching, are some topics of fannish discussion.
Views on when and how it is acceptable to scanlate something can vary among fans and fan communities, and where exactly the ethical line falls has been the subject of plenty of debate, with some scanlators attracting controversy or wank for violating certain unwritten rules.
Scanlation ethics have also evolved considerably over time. For more detail on the historical development of the scanlation community, see: History of Scanlation.
General ethics of fan localization projects
The ethics of scanlation closely mirror the ethics of other fan-produced localization projects such as anime fansubs and video game emulation. Though all of these projects may be legally considered piracy, fan localization communities have formed ethical conventions based on meeting certain goals—such as increasing access to media (for the benefit of fans), increasing the media's reach (for the benefit of the original creators, and for the financial success of a franchise), commitment to fidelity and/or transparency in translation, and proper attribution of the fan labor involved.
One reason for this is given in the scanlation team Shi-Ran's mission statement:
- We hope that by our efforts readers will gain an increased appreciation of the work of so many talented women's comics writers and illustrators, and that ultimately our projects will encourage visitors to support the mangaka by buying their own copies of their works. 
Early generations of scanlators usually dropped series that got licensed. However, today, the majority of scanlators continue working, but encourage people to buy the official release once it becomes available.
Available yet delayed official release
One reason many groups continue scanlating licensed series is that official translations are usually years and years behind the source country, especially for an ongoing series -- in the case of manga, domestically licensed versions are often not released until 2 - 3 years (or longer) after their original publication in Japan. On top of this, release schedules for domestic manga volumes are usually much slower than the release schedules of the originals, so official translated versions continue to fall further and further behind.
A good example is the popular series One Piece. Prior to 2010, new volumes were released at a snail's pace, with fewer than twenty volumes available in the US. Meanwhile in Japan, there were over fifty since on average, four new volumes are released each year. A fan could read the weekly chapters in scanlations a day or two after their release in Japan, but if they waited for the US release, it would have taken over a decade to catch up. This discrepancy changed in 2010 when Viz sped up the English-language releases. From January to June of 2010, five volumes were released each month before going to a four volume per year release schedule in 2011. By the end of 2011, 59 volumes were available in the U.S. compared to 64 in Japan.  This is on par with the speed of Naruto's release schedule. 
Discontinued, out-of-print official release
Even groups that frown on scanlating licensed titles usually find it acceptable to scanlate series that have been dropped by their non-Japanese publishers (so the official translation is incomplete) or whose official translations are out of print.
Licensed, never released
Many companies license more series than they publish official translations of. While some groups refuse to scanlate any series that has been licensed, others reason that it's not unethical to scan something if a publisher is just going to sit on the rights and not produce a version that fans can actually purchase.
Contested official release
Some groups scanlate series whose official translation is seen as being of poor quality, or too heavily localized or censored; other groups find this practice unethical. This is much more controversial than scanning material that is unavailable (as with series that get dropped by publishers or where the official translation is years behind the original language version).
In late 2019, Viz Media shut down several fan scanlation-hosting sites—including MangaRock, Mangastream, and Jaimini's Box—essentially leaving the official translation of One Piece as the only translation available to English-language readers, many of whom preferred the fan scanlations (notably, many One Piece fans universally prefer the name Zoro to the officially localized "Zolo", among other translation differences). On 7 January 2020, Artur, a One Piece super big-name fan publicly criticized some of the translation choices made by the official translator, Stephen—himself a former fan scanlator. Artur's public criticism was in turn criticized for being presumptuous, inaccurate, and irresponsible (even incendiary) given the size of his following. 
Whether scanlating doujinshi should be different from scanlating manga has been the cause of some debate. General fandom view tends to be that scanlating and sharing doujinshi is more lax than scanlating and sharing manga. This may be because doujinshi is amateur-published, sold, and usually based on a pre-existing work, instead of an original piece published officially by a company.
Scanlating doujinshi is generally done without the permission or knowledge of the doujinka (doujinshi artist), which is similar to how manga is scanlated. However, some fans feel scanlating doujinshi should be given the same consideration as asking permission to use fanart for English-speaking fanartists, or as asking permission to translate English-language fanfic into another language. Other fans disagree since doujinshi is being sold; in online fandom pieces are shared freely, but the exchange of money changes the situation from the usual fandom dynamic the scanlators are used to.
While a few Japanese fans have given permission for their doujinshi to be translated as text files or scanlated, most have not given permission, and usually are not asked. Since scanlating is usually on forums or communities in other languages, many may not be fully aware of it when it happens with their work. Some doujinshi artists have been flattered by the attention; others are horrified at the idea and have asked the translators to cease distributing their work.
Raws are scans of manga or other material in the original language. Some raw providers upload their scans to websites where anyone is allowed to download them or use them for whatever they want. Many scanlation groups allow others to use their scans but ask to be credited for providing or cleaning them. Some groups are happy to send their raws to other scanlation groups (for scanlation into a different language, for example) if they promise not to post the original language version publicly (since speakers of that language already have access to a commercial version).
In the past, many scanlation groups considered it highly unethical to start scanlating a series another group was already working on or had announced the intention to work on. At one time, "poaching" referred to creating a new scanlation—even from complete scratch—after another party had already claimed the source media as their turf.
Sometimes when a group's project became popular or inactive, others groups would try to scanlate the same series in order to attract more visitors or to continue the stalled scanlation. SnoopyCool inadvertently (and famously) took over several projects like Flame of Recca from other groups, leading to some interesting drama, and later became victims of project poaching themselves. When Evil-Genius first came into the scene, the group attempted to scanlate a large number of popular series already being scanlated by other groups (usually at a lower quality), much to the dismay of other groups.
[S]canlation groups often viewed their projects as their "turf." As such, whenever a group would start the same project, there was usually a public confrontation over the project on IRC or via email. In 2005, the scanlation scene was still relatively localized to IRC with many scanlators hanging out in the same channels. ...[T]he stigma attached to being labeled a "project stealer" would usually preclude groups from joint projects with more reputable groups and did impact the reputations of groups among scanlators.
An example of scanlation drama over a project from 2005 is demonstrated in this chat log between the scanlation groups DragonVoice and Inane, posted at DragonVoice's site:
<riseabove77> i'm an op at dragonvoice
<riseabove77> might sound familiar to you
<riseabove77> since you stole a project from us
<riseabove77> the moonlight that surrounds us
<riseabove77> we released chapter one of that over a month ago
<Aliera|away> oh, i didn't know you owned it ~_~
<riseabove77> well, that's true
<riseabove77> i don't own it
<Aliera|away> anyway, we're doing the tank version
<riseabove77> but there is a code of ethics in scanlation
<Aliera|away> which came out last month
<riseabove77> which you obviously don't follow
<riseabove77> what's the difference??
<riseabove77> same fucking story
<riseabove77> this is an excelent way to get a bad reputation
<riseabove77> by the way
<Aliera|away> oi, we picked it up from chapter one
<riseabove77> so did we
<Aliera|away> and we've been planning to do this project for over a year
<Aliera|away> do whatever you want
<riseabove77> it was on OUR fp list for a year to
<Aliera|away> but if you're here to pressure me to drop the project
<riseabove77> no, i won't
<riseabove77> you obviously have no honor
<riseabove77> or you wouldn't have done this
<riseabove77> i just wanted you to know that this will get around
As scanlation groups have gotten more numerous, views on poaching have shifted. Nowadays "poaching" often exclusively refers to a new party starting a divergent scanlation partway through a series, based off the earlier contributions of another party, without permission.
From a February 2015 discussion regarding the possible takeover of the fan translation of the light novel Stellar Transformation (ST):
You don't translation poach. I've said it before and I'll say it again - It's a huge dick move, and one which will get you a really bad reputation amongst many in this circle. There are so many works that are available, especially in the Chinese => English field. A decent, honorable translator will find his own fanbase instead of just trying to steal another work’s.
Did another translator contact the current translator? I'm talking about an actual translator that can do a better job. Is the new translator up to the task and won't suffer the same fate? Is the new translator a translator and not a MTL [machine translation]? ...If the "handover" isn't initiated by another translator, then the leecher is another self-entitled egoist looking out for himself.
Poaching shouldn't happen at all unless there's ZERO contact from the original translator, the project is put on hiatus or abandoned all together. It's common courtesy, it's common sense, it's basic decency. Why do you think no one picked up ST after he-man stopped TLing [translating]? It wasn't until confirmation that the he-man has to abandon it due to work that others translator came to see if they should pick it up.
The first and foremost is COMMUNICATION, which a lot of leechers and first-time/new translator doesn't seem to understand, you TALK and see if a collaboration can be done first, most of these people "poaching" cannot even do this GOD DAMN SIMPLE STEP. They OBVIOUSLY read the TLed [translated] work by the current translators, otherwise they wouldn't know where to start (it's a different thing if it was an unannounced project/simultaneous release). Yet somehow the original TLer should reach out to someone who metaphorical slap them in the face? You are kidding me right?
As for at what point should another translator step in, refer to step one. Again, communication. If another translator wants to take over after a reasonable timeframe (is it a holiday? is it exam period? is it crunch time at work? etc...) elapsed and something can't be work out, then it will be up to the current and new TLers to figure what's going to happen. If it's someone unrelated to the translation (ie. a leecher) is pushing for it, well, to your coaching analogy, the leecher is acting like a parent who's playing arm-chair coach that's screaming and cursing at the team for failing to do what S/HE thinks is the right play.On the other hand, if the new translator is on par with the old translator, and the old translator refuse to work due to an unreasonable excuse, then the two will figure out what's going to happen. Be it two separate releases, drama and what not...
Poaching a series may still lead to wank.
Scanlations of scanlations
Many scanlation teams do their translating off of a previous scanlation. This is especially common from English into other European languages. Some parts of the scanlation community consider this highly unethical without prior permission. Scanlation groups often publicize their policies on this (a typical policy might be that anyone is free to translate from them, but they'd like to be credited).
Most scanlators consider it highly unethical to turn someone else's text translation (often called a "script" in this context) into a scanlation without prior approval. Some translators merely wish to be notified and credited. Others disapprove of scanlations and will abandon a translation they find being used for this purpose.
Issues regarding for-profit scanlation-hosting sites
Very troubling to many scanlators, some sites host other group's scanlations for profit from users, using the hosted scanlations as a means to obtain revenue through paid memberships, excessive donations, or advertisements. Since the great majority of scanlators work for free and distribute their scanlations for free, this can be considered offensive, an exploitation of the scanlation groups, and a violation of scanlating or fannish ethics in general. Because hosting and serving scanlations takes significant bandwidth resources, many scanlation download sites which may not have strictly unethical intentions do in fact ask for donations to cover server costs—these activities walk a fine line between a necessary evil and creating any appearance of profit, which is widely viewed as unacceptable.
One of the most notorious examples of this practice is NarutoFan.com, started by user Tazmo in 2002, which effectively sold anime fansubs and manga scanlations of many series through paid memberships. Many groups requested that their scanlations to be removed from the site, but their requests were not granted.
Some argued that what [scanlators] were doing was illegal in either case, Tazmo was just being a savvy businessperson. Others argued that since free scans and subs by the community was a legal grey area (since most of it was unlicensed in english) that charging money for it moved out of the grey area and into the red area, perhaps garnering unwanted attention and leading to legal action against the fansubbing groups as well.
There was a concerted fan campaign to get NarutoFan shut down. Circa 2004, the website StopTazmo.com was registered as a counter-site that spread awareness of NarutoFan's practices, and also hosted scanlations for free. Additionally, some scanlation works began embedding pages that condemned NarutoFan and other paid scanlation-hosting sites.
OneManga also caused controversy for hosting other groups' scanlations for online viewing, without permission from the groups to do so. This caused problems not just because they were making money through advertisement and using the scanlations for viewers, but also because they were drawing attention away from the scanlation groups doing the work, and for hosting the images at a severely down-graded visual quality. At least initially, requests to have scanlations taken down were not granted, though they later developed a policy where they might take down scanlations in certain circumstances.
- Inside Scanlation: Scanlation Drama
- "[Naruto Fandom] Concerning Narutofan, Tazmo and his controversial business practice" by badniff
- Reddit: r/ScanlationDrama
- see, for example, Nakama's dropped projects page. Accessed 29 October 2008
- August 3rd 2003. Shi-Ran Mission Statement. Archived 21 October 2008.
- That_guy_why. "[Manga] Weekly Shonen Jump Jumps the Gun on Manga Pirates Pirating Manga about Pirates" posted to Reddit.com/r/HobbyDrama on 21 Dec 2019.
- Wikipedia, List of One Piece chapters, (Accessed 4 December 2011)
- Wikipedia, List of Naruto manga volumes, (Accessed 4 December 2011)
- coffee-mugger. [ONE PIECE] Official translator gets into a long and public argument with big-name fan, posted to Reddit.com/r/HobbyDrama on 12 January 2020.
- Inside Scanlation. "Scanlation Drama". (Accessed Apr 2021.)
- DragonVoice and Inane. Chat log. 2005.
- sumguyoranother. Ethics of translation poaching, posted to Reddit.com/r/LightNovels on 5 Feb 2015. (Accessed Apr 2021.)
- rwxwuxiaworld. Ethics of translation poaching, posted to Reddit.com/r/LightNovels on 5 Feb 2015. (Accessed Apr 2021.)
- badniff. "[Naruto Fandom] Concerning Narutofan, Tazmo and his controversial business practice" posted to Reddit.com/r/HobbyDrama on 17 Jul 2019. (Accessed Apr 2021.)