Yeah this topic is not a good one. As others have said, since it is people who decide what flawed is, and people are inherently flawed, the system could never be anything but flawed. Humans have long since left behind evolution, using medicine, science and technologies to overcome limitations. The only real way to force eugenics in a neutral manner is to remove that medicine, science and technologies and have people work for survival, and that would only work if everyone was forced into it.
Euthanasia should be legal on the other hand, but only as an option and the patient being the one to decide. Those people in advanced stages of cancer or AIDS get pumped full of drugs only to draw out their inevitable death, they should have a choice. Someone who is completely paralysed too should also get a choice, being stuck in a wheelchair your whole life without even being able to breath without help would be cruel. Forcing it like Newtonscat describes is wrong.