Air space local rule for the 2015 Hang Gliding Worlds:

Controlled airspace infringement, horizontal or vertical: Zero for
the day. Airspace infringement is proven when the track is more then 30m
horizontal or vertical within the airspace. Barometric altitude used by default.

Paragliding Sporting code rule used at the latest Worlds:

Where the pilot's track log is recorded closer than 20m from
prohibited airspace, vertically or horizontally, a penalty of 2% of the pilot's
task score per meter shall be deducted, resulting in a zero score 30m within the
restricted zone. The entire flight from launch to landing will be considered for
such violations, regardless of the task being active, the course started or
finished.

Apparently GPS altitude was used but the CIVL Paragliding Sporting
Code states:

14. 4.5 Airspace Infringement and Cloud Flying Where infringement
of airspace is considered possible it is the responsibility of the pilot to
produce tracklog or barograph evidence that this did not occur.

The Hang Gliding Sporting Code states:

2. 29.2 Controlled Airspace

The organisers shall specify in the local regulations or at briefing, controlled
airspace or other areas where flight by competing gliders is prohibited or
restricted. Such areas shall be precisely marked on published maps. Such areas
shall be precisely marked on published maps and provided as openair.txt format
files for display on instruments and scoring check. The organiser may establish
prohibited airspace that may differ from official airspace as needed, and this
airspace created for the competition shall be treated as official airspace with
the same penalites. Pilots whose recorded track comes closer than 100m
vertically or horizontally to prohibited airspace shall be listed in the scores
for each task without penalty. Where the pilots track log is recorded more than
30m inside prohibited airspace, vertically or horizontally, the pilot shall
score zero for the day. The entire flight from launch to landing will be
considered for such violations irrespective of task being active or stopped, the
course started or finished.

15. 4.6 Altitude Infringements Where vertical infringement of airspace, cloud or
briefed altitude limits is considered possible it is the responsibility of the
pilot to produce track log or barograph evidence that this did not occur.

Barograph altitudes are used.

Penalties for airspace infringements at the 2015 Green Swamp Sport Klassic, the
2015 Quest Air Open National Championships, and the 2015 Big Spring nationals
are at the discretion of the meet director. I don't recall there ever being air
space infringements at these meets or similar ones in the US.