The ASA guidance includes these images of the kinds of suits that are included by the new guidance:
The guidance also includes examples of suits that the revised rules will continue to exclude:
There has been some predictable grumbling on social media about the changed rules potentially serving as a back door to performance enhancing body suits, but this is clearly not the purpose or consequence of this ruling. It's also important to note that this is distinct from recent FINA changes to the rules about wetsuits in competitive open water swimming, which have also caused controversy in the open water / marathon swimming / triathlon communities. Instead, this new guidance is simply a way of enabling more women and girls to compete in swimming, and that has to be a good thing.
BME communities are notoriously poorly represented in swimming (all kinds, all levels). This is due to a combination of factors including lack of access to affordable swimming lessons and facilities and the lack of perceived 'fit' with the sport (i.e. children being pointed towards other sports, or being told that 'black people can't swim' because of outdated and racist assumptions about bone density). This poor representation is particularly true for women and girls. There is also the legacy of the historical exclusion of non-white people from swimming facilities - for example, during segregation in the US (see Wiltse's 2007 book, Contested Waters, for a frank and disturbing account of this) - which has ongoing generational impacts in terms of facilities, expectations and a paucity of role models.
So this small change in the swimwear guidance isn't going to solve the problem of the whiteness of swimming, but it is an important beginning, and signals the active valuing of participation and inclusion to those outside of the sport who might like to give it a try.
And this got me thinking about other branches of the swimming world where strict costume rules apply, including marathon swimming. This is a sensitive and hotly contested area, but it seems to me that marathon swimming is in a position to be among the leaders in the field of amateur endurance sport by actively incorporating amendments of this kind to swimwear rules. Changes like this to the regulations by Channel / marathon swimming governing bodies are relatively costless, since they would not confer a performance advantage on swimmers wearing full body costumes, but would demonstrate an openness to the social diversity that is currently lacking. It's a small measure, but one that I think would speak volumes in welcoming new swimmers to the marathon swimming community.