Apparating Out of a Tight Spot

[Cindy C.]

No: HPFGUIDX 29137

I was wondering what the "rules" regarding apparating might be.  The 
thing that got me wondering is the Shrieking Shack scene in PoA.  
Once Snape arrives, Lupin and Black are in danger of being captured 
and kissed, yet neither apparates out of the Shrieking Shack to 
safety.  Pettigrew is about to be killed in the Shrieking Shack, yet 
does not apparate, although he must know how because he is a DE.  Why 
don't these characters just apparate themselves out of trouble?

The books give us a few rules about apparating and disapparating, and 
maybe we can discern a few more.

Apparating Works Best Over Short Distances:  We are told that 
intercontinental apparition is difficult, and it becomes imprecise 
over long distances.  

You Can't Apparate at Hogwarts:  Starting in PoA, we are told that 
you can't apparate on the Hogwarts grounds, and this is drummed into 
us again and again in GoF.  

Apparating Is Difficult and Risky:  In GoF, we are told you need a 
license to apparate, that it is difficult, there is the risk of 
being "splinched," and many wizards don't bother with it.  

It Is Possible to Apparate Within a Structure:  Percy apparates 
downstairs at the Burrow for practice.  

An Incantation Is Unnecessary to Apparate:  When Bagman disapparates 
in "The Dark Mark", he was "looking quite distracted, and without 
another word, he Disapparated with a small *pop*!"

There are a few more rules that have not been stated explicitly, but 
that make sense.

You Can't Have "Passengers" When You Disapparate:  If you could carry 
passengers, then Lily could have apparated herself and Harry out of 
Godric's Hollow when Voldemort attacked.  Mr. or Mrs. Longbottom also 
could have grabbed Neville and disapparated when the DEs appeared.  
Also, in GoF, Arthur Weasley apparates out of Privet Drive, but sends 
the boys using expensive Floo powder. 

Apparating Requires Strength:  After Harry and Krum meet Mr. Crouch 
on the Hogwarts grounds, Harry observes that Mr. Crouch looked too 
weak to apparate.

You Can't Apparate at Azkaban:  On the list, some of us have 
speculated that Azkaban is another place from which you can't 
apparate.  That makes sense, or dark wizards would do things like 
apparate into Azkaban and help their fellow dark wizard escape.

Open issues appear to be:

Can You Apparate From Inside A Structure to Outside?  This could 
explain why Pettigrew, Lupin and Black don't attempt to apparate out 
of the Shrieking Shack into Hogsmeade.  When Percy, Bill and Charlie 
apparate to the QWC, they apparate into the woods, not directly into 
the tent (although we don't know if they left from inside or outside 
the Burrow).

Do You Need A Wand To Apparate?  In GoF, we see several people 
apparate and disapparate, and there is never mention of a wand.  In 
one instance, a wizard says "See you later Arthur" and then 
disapparates, which makes the whole process seem somewhat casual.  
When Bagman and Crouch disapparate together, Crouch nods, Bagman 
waves, and they disapparated.  This hardly seems like what we 
normally see with complex magic – concentration, wand waving and an 
incantation.

Also, Hagrid appears to disapparate in PS/SS ("[Harry] blinked and 
Hagrid had gone") when he leaves Harry after Diagon Alley, and Hagrid 
doesn't have an intact wand.  If a wand is required to disapparate, 
one would think that using a snapped wand for a difficult spell would 
be dangerous or even impossible.  Also, Fudge speculates that Sirius 
must have disapparated at the end of PoA, but Snape corrects him by 
saying you can't disapparate off the Hogwarts grounds.  If a wand 
were required, Fudge's statement doesn't make much sense because  
Fudge should know Sirius has no wand after years in Azkaban and after 
being apprehended again that night at Hogwarts.  

On the other hand, if apparating requires a wand, that would explain 
some potential plot holes.  Lupin and Black didn't have access to 
wands when Snape appeared in the Shrieking Shack (Lupin being tied up 
and Black having no wand), so they couldn't apparate.  Pettigrew 
perhaps doesn't have a wand, which explains why he doesn't apparate 
away when Black and Lupin are about to kill him. 
 
Anyway, do these "rules" and inferences make sense?  Are there any 
other possible "rules" of apparating and disapparating, particularly 
rules that explain why adult characters (particularly Lupin, Black 
and Pettigrew) don't apparate their way out of trouble? 

Cindy