Dunno about that, if they couldn't nail you with their radar you'd
probably be breathalysed!  :)

Looking at

http://www.austlii.edu.au/cgi-bin/sinodisp/au/legis/qld/consol_reg/toumrr1999629
/s125.html

and in particular (b), I think farmer Joe is OK even if he doesn't pull
over, because he is not driving abnormally slowly (I'm assuming here
he's driving a tractor or some such vehicle, and not his 4WD). The
section doesn't define "abnormally slowly", but I think the
circumstances would have to include the type of vehicle. At least, I
cannot see why the type of vehicle should be excluded from the
circumstances.

The figure of 20km/hr may have been a misreading of the example in this
section, which talks about driving *at* 20km/hr, not driving at 20km/hr
less than the speed limit. I'd be surprised if a charge of obstructing
drivers could stand up if a person were doing 59 in an 80 zone, no
matter how annoying it might be to others.

Of course, if people just pay the fine rather than go to court, then all
bets are off.

Sylvia.

Obstructing traffic laws should be used on the highways, Sunday driving
to Tamworth got stuck behind a line of around 15 cars coming out of
Scone doing around 80k's, on the straight I could see a silver Lancer up
the front, ok must be an L plater sit back and wait for everyone to
overtake, one or two got around, get to Parkville at the 80 zone and the
brake lights come on every car in front the person up the front had
slowed to 60 in the 80 then sped to 80 at the 100 sign, same deal
through Wingen most finally get a chance to go round the Lancer at the
over taking lanes at Burning Mountain, turns out it wasn't an L plater
but a woman in her 50's and to top it off she was turning and smiling at
the cars overtaking her.

Mus have been one of these on a crusade to drive below the speed limit
to keep the road toll down.

You misspelt "don't care"

Sylvia.