I have to say, this is not the sort of attitude I expected to find on this site. Especially from someone defending cheating on exams. Anyway, I'm sure I won't convince you to change your mind on this, and you certainly won't convince me.
And I find it somewhat bizarre that you seem to think there is no moral value in following the law? Especially when I added the caveat "if there is no other conflicting moral principle", which means you believe there is nothing bad about the law?
Or is it the caveat you disagree with, and you think the law must be followed no matter what?
No, I don't see any moral value in following the law. Following the law can be and often is morally good by coincidence because the law encodes some piece of morality, e.g. the laws against theft or murder. But if the law says I'm only allowed to cross the street at designated locations, and I can safely cross at a different location, there is no moral issue with doing so, in my view. If speeding is immoral it is only because of the safety concerns, not because it's illegal. If I refrain from speeding on a road where I believe it's safe to go significantly faster than the limit, it's only because I want to avoid the potential consequences of breaking the law, not because I think it's somehow wrong.
Just so you know, that's not a position most moral philosophers take, as long as the law is decided by sufficiently democratic procedures.
The fact that you belong to a group of people, and the people decide on rules, means that violating those rules is a moral violation against that community of people.
To say that has no moral weight at all is a pretty extreme position. Now obviously if there's a conflict with another principle, there are times that other moral principle should win. But to say that there is no moral value whatsoever in following the law is not something I think many people will agree with. And thank goodness.
Not that it's going to change my view, but I'm curious if that's really the position they take.
And "sufficiently democratic" basically means freedom of political speech, adult citizens can vote, representatives are chosen by majority rule, elections are fairly conducted and not rigged, and laws are passed by majority rule.
Obviously you can always quibble over details such as unicameral vs bicameral legislatures, single-member district vs. multi-member district representation, gerrymandering, judicial review, and so forth.
But if people are allowed to freely debate and the franchise is universal and elections are free and fair and elections and decisions are based on majority rule, then those are the basic conditions. So the US and France and the UK are sufficiently democratic; Russia and Iran and China are not (despite holding elections).
Edit: actually I do have one other thing to say. It's quite a coincidence that the conditions you laid out happen to be those that were met in the US right about the time that book came out. Feels like it might have been working backwards from the conclusion.
I'm not even defending it. I'm just describing the mainstream ethical foundation used today.