More tips from an experienced and successful attorney who wishes to be unnamed:
In an undercover cop case, it's helpful to know their procedures. With hand to hand sales, usually the undercover is dropped at or near a location by other members of the team. Sometimes they drive by and make a purchase from the car. They wear electronic recording devices called Kel Kits which are monitored by the back-up team. The undercover walks up to someone, makes a transaction, and then when the are out of earshot call out to the team "done deal". They have a code word to use during the transaction if they get in trouble. The team will then send in uniforms or perhaps other undercovers to grab the suspects. The undercover will drive by in an unmarked car with another officer (who will probably radio the uniforms that they're coming so the undercover's voice isn't recognized). The ID is done while moving - driving by, as the suspect(s) are on the sidewalk, perhaps with a grass median between the sidewalk and the street. Although the undercover team will claim there was nothing obstructing the view of the undercover officer, the uniforms or other undercovers will most likely pull up to the address where the buy took place (instead of down the street, giving notice to the suspects and an opportunity to run). A uniformed cop may testify to this. The undercovers won't. Although the
officers may have a description of the seller, they may grab everyone in the area whether or not they match the description, and put them in the show up.
Undercover officers have access at RPD to surveillance equipment, and do use it in a variety of circumstances (which they will claim don't apply in your hand to hand sale case). They have unmarked cars and vans outfitted to look like civilian vehicles, from which audio or video can be used to record what's going on. They have mini video recorders which look like buttons that they can wear on their clothing. These can be things you can use to argue that there was a lack of evidence in your case.
If the officer claims he was in danger, and that's why he didn't observe the discrepancies in clothing or appearance between what he called out and what your client looks like, consider whether the recording reflects a fearful tone, whether the code word was used (it wasn't or the team would have come in) and whether, since the officer knew his fellow officers would be responding and wouldn't want to endanger them, the undercover officer called out on the recording used to ensure the safety of officers (remember, that's the reason they use it - at least that's what they say to explain why details of descriptions aren't important) to other officers
about the particular menace or danger of this individual.
If yours is an ID case - they grabbed and identified the wrong guy when the back up team came in - consider the time between when the sale occurred and when the arrests happened. If the recording indicates a particular time that the detail commenced, the cop may claim that they paused the tape. Listen for any pauses, and be aware that they may come up with this. And listen for the DA's direct, "directing your attention to (date) at (time), what were you doing? Which time did the DA open and question on? Consider when the back up team was asked to be in the area.