Some time back someone was complaining about a superior giving orders that they did not feel comfortable carrying out (I believe this was for a Corpsman that was in Afghanistan).

Here's the gist of the JAG briefing given at OCS:

If you believe an order is illegal or immoral, ask the person giving it to explain the intent and desired outcome.

If that doesn't answer your doubts, respectfully object to carrying out the order. Then document the names of witnesses and the time and date.

Then carry out the order.

If you do not, then YOU violate UCMJ Article 91 or 92.

Once you get back to the rear, seek out legal and give them the information for investigation.