The COLREGS are the official rules of the road governing the operation
of boats (and ships) in international waters.

They can be found he

http://www.jag.navy.mil/distrib/inst...OLREG-1972.pdf

Like all governmental publications they can be a little muddy to read,
especially in the beginning. The good stuff starts at about Page 13.
In order to obtain a USCG Captains's license you must pass an
examination on the rules of the road with a minimum passing grade of
90%.

Rules 6, 7 and 8 beginning on page 18 are particularly relevant and
set the ground rules for responsibility.

Rule 15, Crossing Situation is also particularly relevant:

When two power-driven vessels are crossing so as to involve risk of
collision, the vessel which has the other on her
own starboard side shall keep out of the way and shall, if
the circumstances of the case admit, avoid crossing ahead of
the other vessel.

Notice the words: Avoid crossing ahead of the other vessel.

Rule 13, Overtaking is interesting also and may be relevant in the
case of the destroyer. In my experience a vessel overtaking on the
starboard side with a converging course frequently leads to a messy
situation, even with relatively small, maneuverable boats. With very
large boats it can turn really ugly if the situation is not
recognized, and acted upon, well in advance. Basically Rule 13 (Page
25) says that the overtaking vessel remains burdened with the
responsibility of keeping clear even if on the starboard side, and
even if forward of the beam. That's a very important distinction
which I've seen ignored by people who should know better. It may very
well appply to the freighter in this collision if they were originally
overtaking the destroyer. Since we don't know their relative speeds
it's not clear if this applies or not but the rules are clear.

Last but not least Rule 17 on page 29 talks about the responsibility
of the "stand-on" (right of way) vessel to do anything possible to
avert a collision if it becomes cleary necessary. That is why blame
is frequently apportioned in the final analysis.