Ethical Conduct : Right Action
Śīla : amyak-karmānta

The second ethical principle, right action, involves the body as natural means of expression, as it refers to deeds that involve bodily actions. Unwholesome actions lead to unsound states of mind, while wholesome actions lead to sound states of mind. Again, the principle is explained in terms of abstinence: right action means 1. to abstain from harming sentient beings, especially to abstain from taking life (including suicide) and doing harm intentionally or delinquently, 2. to abstain from taking what is not given, which includes stealing, robbery, fraud, deceitfulness, and dishonesty, and 3. to abstain from sexual misconduct. Positively formulated, right action means to act kindly and compassionately, to be honest, to respect the belongings of others, and to keep sexual relationships harmless to others. Further details regarding the concrete meaning of right action can be found in the Precepts. (From The Big View)

This principle reminds me of a Kahlil Gibran quote I encountered recently: "If the other person injures you, you may forget the injury; but if you injure him you will always remember." A person who has incorporated the previous principles into their lives will find it difficult to forget harm caused to others, leading to an unsound state of mind. A person who's actions are wholesome has little to worry about since in not harming anyone, they will generate nothing but goodwill from the people they encounter. The first explanation above talks about causing harm to come to sentient beings. I've talked extensively about this in previous posts as it regards my decision to stop consuming animal products, but it brings up another point, that of suicide. I can't help but think of a situation where one would have to likely sacrifice one's own life in order to save others. I would think that this would still be considered right action even though the result was essentially suicide, as the good caused by saving others outweighs the negative of what is essentially suicide. The second explanation speaks to the classics of lying, cheating and stealing. These seem pretty self evident. The third talks about sexual misconduct. This gets a little thornier as the times have changed a great deal since the time the sutras were written. Ultimately, though, it all comes down to not causing harm. Sexual and relationship issues, though, are pretty darn complicated. For instance, let's say Guy A is interested in Gal B, but Guy C is also. If Guy A and Gal B "hook up", that causes harm to come to Guy C, does it not? Does the good generated by the mutually consensual relations between Guy A and Gal B outweigh the harm caused to Guy C? It all makes my head spin and reminds be of a cartoon I saw recently

XKCD Comic