Just How Far SHOULD A Mother's Loyalty Go?

I don't know about you, but in my book, liars and thieves are the scum of the earth. 
But apparently not everyone follows this line of thinking. 
So here's my question of the day: When is it WRONG to stand up for your child?

But first, a quick look into why I ask this question.
I won't bore you with the 'Jerry Springer' details, but let's just say our weekend was abruptly interrupted with vandalism and thievery of an extensive nature - Our Halloween display, which we've set up every year for the past ten years - without incident I might add - was violated beyond repair, with much of it stolen, on 3 separate occasions - 2 of which happened  Saturday night.  But luckily, much to the surprise of our criminals, we were poised and ready for them on the third attack, literally catching them in the act.  Of course it turned out to be 3 older teens - high school seniors as we found out - using mommy's SUV as the getaway as we chased them down the street, memorizing the tag number. 

Fast Forward: I'm the one (NOT the cops) that located said guilty party by way of fate, no less - pulling up behind the Jeep Cherokee at a stop sign in front of my house.  BUSTED!
Police were called once again - 'altercations' between our families ensued, with the mother of the teen insisting her 'angelic football playing son' was innocent beyond doubt, not ever questioning him for the 'facts', and making it even worse by lying for him, posing as his alibi  - and if that wasn't bad enough, she made US out to be the criminals for 'harassing and detaining' them on their property while awaiting the police.  (Which by the way, she conveniently urged her son and his accomplices to leave  before the police arrived because they had a 'movie' to catch.)  
I couldn't help but shake my head in disbelief!  Was this for real?
Back in my day, I do believe my parents would agree the movie would wait, and my ass would be sitting there explaining my side of the story - first to the accusing neighbor, then to the police.  I guarantee my parents would not of let me flee the scene - in the accused vehicle - to fulfill a movie date of all things!  Well hello, apparently this mother does not 'parent' in that manner.  Instead she stood her ground, calling us every name in the book and accusing us of harassment. Oh how times have changed!  Is this what a loyal mother does?

Trust me, I know the pull of a 'mother's loyalty' as I have a 25 year old son myself.  But I also know boys do stupid things - and my first priority was always to find out the truth, not to cover up for my guilty offspring.  Just what is she teaching these young men?  That you CAN do the crime and get away with it, if you just know how to work the system - Jerry Springer style?  Well, apparently it works. 

Sadly, I am more than aware of this protocol.  In my experience with the police, they are 'johnny-on-the-spot' to bust you for something, but never there in the same way when you need their protection or justice.  And they wonder why people take the law into their own hands!  So of course this case quickly turned into a 'their word against yours' with the victim coming out short changed...hum.  Once again 'the man' fails me.  Why was I even surprised? 
(Spoken like a true hippie, huh?)  Uh, sorry, that's another post for another day...back to the question:

So again I ask, where DOES a mother's loyalty lie?  Is it all about covering up for your child's behavior or is it about teaching your child right from wrong, even if it stings a little? 

In my day the motto was simple: Don't do the crime if ya can't do the time.  Where are our children heading if they never know this simple rule?  

So to that 'mother' of which I speak of in my neighborhood - If you think you're doing your kid a favor now by covering up these petty shenanigans, what are you going to do when the crime involves something a little more serious, like a weapon or someone's life?  And oh, when all the little kids ask why we are no longer putting on our yearly Halloween display, I'll give them your address and tell them to go ask the innocent football players.