The phrase "to outweigh the harm" means that the positive effects or benefits of something are greater or more important than the negative effects or harm it may cause. Full definition
They accept any application of genetic and medical technology so long as desires are fulfilled and the benefit outweighs the harm to individuals, classes or society as a whole. (religion-online.org)
Because «research has not yet proven that the potential benefits of testing outweigh the harms of testing and treatment,» it says, men should discuss the pros and cons of PSA screening starting at age 50 (but 45 if you're African - American or have a father or brother who had prostate cancer before age 65). (scientificamerican.com)