Equity should be used instead of equality in many social situations. You can easily find out that. Sometimes it is not perfect to have total equality regardless of ones' background, situation etc. Therefore we should use equity in justice system also and treat everyone with equity but not merely equality
The society we are living in now works with equity. Sometimes what we need is equity but not equality especially when the person we are treating have obvious difference (one is normal while one is mentally retarded). Equality may not work in this case Hut equity may work in this case.