Helping Others Who Still Need to Suffer due to karma I was wondering if helping others who are suffering prevents them from receiving their karmic dues. 

For example, if Person X caused great suffering to others, then according Buddhism, his Karma will come back to haunt him in the same life or a next life. Now suppose, he does suffer in another future life but a Good Samaritan rescues him before all his karmic debts are paid. The Good Samaritan improves his karma account with the good deed but he has still rescued someone who still has a debt to pay to society. 

How can one justify helping others in this case? I'm not trying to find fault with Buddhism.
Karma is not meant as a punishment or retribution or debt to be paid which you are not to interfere with. It is complicated with many interactions. The environment has to fall into place for its results to be seen. 

If the environment can influence the effects of Karma, it can be eradicated or changed in some cases. Since Karma is complex you you cannot say for sure.

By helping others your can help lighten the burden of their Karma and in some cases counteract the bad Karma altogether. 

Also this is the good Karma for the person doing it.