Shoulder Tapping - Davis

Shoulder tapping refers to the illegal process where a person who is not of age asks someone who is of age to buy them cigarettes or, more commonly, Alcohol. Those who are shoulder tapped should be careful as the DPD occasionally runs sting operations targeting those willing to buy Alcohol for those who are not of age.

StevenDaubert notes that they use females older than 18 for said stings, as using minors would be illegal, and using males would get them no hits.

I'm not sure that's true. At least it didn't use to be. When I was 17 I had a girlfriend who was also 17 and did it for the cadets. — BradBenedict

This presents some interesting legal questions: — aa

is this entrapment?

This would not be considered entrapment by any conventional legal interpretation, as entrapment requires that the target be somehow coerced into doing something he/she arguably would not have done had the government not coerced them out of their normal behaviour. No matter how much the minor whines, its not coercion. This is the definitive answer I got from Professor Spriggs (pre-law/"POL150 series" professor here) when I asked him about this specific circumstance last week. Entrapment is a deplorably misunderstood topic claimed erroniously far too often. -KrisFricke

if the shoulder tapper is asked "are you working for the cops?" do they have to answer honestly?

Nope. This is a myth, closely related to misunderstandings about entrapment. See here.

if the shoulder tapee asks the shoulder tapper "are you of age?" and the shoulder tapper answers "yes, i just forgot my ID" and is thus not knowingly providing an underage person with Alcohol, is it illegal?

The following case does not squarely line up with the questions above (really it assumes that 'shoulder tapping' is truly problematic), but I thought it may be interesting reading for those who want to see a recent California Supreme Court opinion on related issues (such as providing alcohol to minors in other contexts): FindLaw link (free registration required).
So, this is secondhand information, but for what it's worth, a friend of mine used to be the person doing the shoulder tapping for the police in San Diego. The kids were told not to lie and say they were overage because that would be entrapment. She also could not lie or use a fake ID if she was attempting to purchase alcohol directly from the vendor. KateBaker
The information provided to businesses regarding alcohol stings says that if you ask the customer (if they actually attempt to buy the alcohol themselves) if they are underage, they are required to tell the truth. They also are not allowed to use fake IDs. —ElleWeber
I heard that when Aggie Liquor lost their liquor license a few years ago it was because an undercover girl used somebody else's ID that looked like her. Maybe DPD doesn't play by the rules. Or maybe I heard wrong. —BradBenedict