Will General Petraeus be court martialed? Will General Allen be court martialed? Will Paula Broadwell face trial?
The answer to each of these questions is likely, "no," with the only possible exception being Ms. Broadwell. Here's why:
Yes, it is true that adultery is forbidden in the military per Article 134, UCMJ, and servicemen and women are routinely punished for adultery. However, this is unlikely in the case of a 4-star general.
First, the U.S. Constitution guarantees all Americans a jury of one's peers if accused of a crime. In the military, this clause has been interpreted to mean anyone of the same or higher rank than the accused. This is to prevent subordinates from sitting in judgment of their military superiors, which is a noble goal. However, in the rare instances of high-ranking officer misconduct, it presents a legally untenable situation. In the case of Gen Petraeus and Gen Allen, the jury pool would have to consist of all 4-star generals. There is also a rule of law that states your jury members should have no bias toward you, i.e. they shouldn't know you and have formed an opinion about you and your crime. What other 4-star general in our military would not know Gen Petraeus or Gen Allen? There are none. On top of all this, Gen Petreaus would have to be recalled to active duty to face trial, another major obstacle for a prosecutor. As a result, these general officers will not face trial, but will instead be dealt with through administrative processes that will effectively end their career.
Paula Broadwell, or perhaps more accurately, Army Reserve Lieutenant Colonel Paula Broadwell, is another matter entirely. Ms. Broadwell's military rank, and the accusations that she mishandled or wrongfully removed classified information (along with the adultery), could very well land her in trial. Her transgressions, however, would have had to occur while she was on duty with the Army for her to fall under military jurisdiction. Expect this investigation to go on for months, if not years. If the investigation reveals a major breach of classified information while on duty, a court martial could be convened. You can guarantee Paula Broadwell's lawyer will go straight to the media if she faces charges but General Petraeus and General Allen do not, and rightfully so, as the hypocrisy will be thick in the air. Expect Lt Col Broadwell to be also dealt with through administrative means that will effectively end her career, but will not be visible to the public.