One of the more complicated topics in the revisions to the 2019 Rules of Golf are the changes to where and how relief is taken from a penalty area.
To get it right, there are four pieces to consider.
TAKING LATERAL RELIEF:
Estimate the point on the line of the penalty area where your ball last crossed, and mark that spot. Then determine a two club-length relief area that is not nearer the hole using your driver. The drop area then becomes the area between that two-club spot circling back to the margin of the penalty area. Your dropped ball (from knee height!) must finish in that drop area. The video on the page linked below explains the process clearly.
TAKING BACK-ON-THE-LINE RELIEF:
A new option for 2019 to take relief after hitting a ball into a penalty area is to estimate the line from the flag to the point where the ball crossed into the penalty area, then dropping along that line within one club length of either side and behind any selected point on that line. The video on the page linked below explains the process clearly.
ELIMINATION OF OPPOSITE SIDE RELIEF:
The past rules option for “opposite side relief” for a red-lined hazard (now “penalty area”) was always complicated, often done incorrectly, and seldom used. New Rule 17.1d removes the option to take relief on the opposite side of a red penalty area. So now a player has just three options for relief, all for a one-stroke penalty: lateral, back-on-the-line, or replay the shot.
REASONABLE JUDGMENT IN ESTIMATING:
New Rule 1.3b(2) says that when a player estimates or measures a spot, point, line, or area to take penalty relief, his or her reasonable judgment is accepted. There are many times when the Rules require a player to estimate or measure a spot, so it only makes sense to rely on the integrity of the player for this decision across all rules. So long as the player did all that could be reasonably expected under the circumstances, the player gets no penalty for small inaccuracies — even if it is later showed that some advantage had been gained.