User blog comment:Braveangel/The longest serving turian and the longest serving human/@comment-217683-20100423032340

Power does tend to corrupt. However, the correlation between time served and propensity to become corrupt isn't really as solid as it would seem. After all, it's not like Saren and Harkin both served well and honorably until one day, they just snapped and became corrupt. They were both bad eggs to begin with. Look at Saren's behavior all throughout Revelation. And Harkin was in trouble with C-Sec all throughout his career with C-Sec. It wasn't the time and power that did it to them, they did it to themselves.

As for Shepard, if Shepard was a paragon and saved the Council, which would likely be necessary to stay the longest serving human Spectre, there is likely a pattern of behavior that would lead away from corruption. As for Shepard being the longest serving Spectre, it's also important to note that, as soon as Commander Shepard became a Spectre, he (or she) instantly became the longest serving human Spectre.

So yes, power does TEND to corrupt. But this tendency is much more pronounced in people who are already prone to that sort of behavior.