EvidenceProf Blog

Editor: Colin Miller
Univ. of South Carolina School of Law

Tuesday, July 28, 2015

Destination Unknown: More on the Cell Tower Pings From Episode 8 of Undisclosed

On yesterday's episode of the Undisclosed Podcast, I noted how Cristina Gutierrez could and should have moved for a Frye hearing regarding the admissibility of the cell tower pings at Adnan's trial. I further concluded that the result of such a hearing would have been (1) the court certainly deeming the incoming pings inadmissible based upon AT&T's own disclaimer that such pings are not reliable for determining location; and (2) the court quite possibly deeming all pings inadmissible based upon the irregularities in how the testing was done (e.g., the prosecutor selectively writing down things called out by the cell phone expert). In this post, I wanted to flesh out the analysis a bit more.

Here's the Frye case. As noted, the defendant in that case sought to admit the results of his lie detector test into evidence. In rejecting his proffer, the court concluded as follows:

Just when a scientific principle or discovery crosses the line between the experimental and demonstrable stages is difficult to define. Somewhere in this twilight zone the evidential force of the principle must be recognized, and while courts will go a long way in admitting expert testimony deduced from a well-recognized scientific principle or discovery, the thing from which the deduction is made must be sufficiently established to have gained general acceptance in the particular field in which it belongs.

We think the systolic blood pressure deception test has not yet gained such standing and scientific recognition among physiological and psychological authorities as would justify the courts in admitting expert testimony deduced from the discovery, development, and experiments thus far made.

In the Daubert case (1993) the Supreme Court rejected this Frye/"general acceptance" test for federal courts and created the notion of judge as gatekeeper, independently assessing the reliability of expert. At least 30 states subsequently followed suit, but not Maryland.

The Court of Appeals of Maryland extensively discussed the Frye test in Reed v. State, noting that

The Frye test has been subjected to some criticism, primarily on the grounds that it is too conservative and unduly prevents or delays the admission of relevant scientific evidence....There are, however, compelling reasons which justify the Frye principle.

Fairness to a litigant would seem to require that before the results of a Scientific process can be used against him, he is entitled to a Scientific judgment on the reliability of that process....

Under the Frye test,...[a]s long as the scientific community remains significantly divided, results of controversial techniques will not be admitted, and all defendants will face the same burdens. If, on the other hand, a novel scientific process does achieve general acceptance in the scientific community, there will likely be as little dispute over its reliability as there is now concerning other areas of forensic science which have been deemed admissible under the Frye standard, such as blood tests, ballistics tests, etc.

As you can see, the Frye test is very conservative/stodgy. It doesn't allow for emerging expert evidence to be admitted until it has general acceptance; even a divide in opinion will lead to exclusion. And the reason for this stodginess is "[f]airness to a litigant." Frye jurisdictions don't want defendants to be convicted on the basis of expert evidence that is of questionable reliability.

Because Frye was extensively discussed in Reed v. State, Maryland courts refer to Frye hearings as Frye/Reed hearings. As I mentioned on the podcast, these hearings are pretty straightforward. As such, there aren't usually ground for a defendant to appeal. That said, sometimes errors are made, as in Clemons v. State, 896 A.2d 1059 (Md. 2006). In Clemons, evidence from a comparative bullet lead analysis (CBLA) was admitted after a Frye/Reed hearing. On appeal, the Court of Appeals of Maryland found that this was erroneous, concluding that

The only consensus that can be derived from all of [the evidence on the issue] is that more studies must be conducted regarding the validity and reliability of CBLA. Although scientific unanimity is not required to satisfy the Frye-Reed test's requirement of general acceptance,...it is clear that a genuine controversy exists within the relevant scientific community about the reliability and validity of CBLA. Based on the criticism of the processes and assumptions underlying CBLA, we determine that the trial court erred in admitting expert testimony based on CBLA because of the lack of general acceptance of the process in the scientific community.

Now, let's return to Adnan's case. AT&T's disclaimer pretty clearly means that the incoming pings would have been deemed unreliable and inadmissible under Frye. Moreover, given that Adnan's case was the first one involving cell tower pings in Maryland, and given the odd way in which the testing was done, I think there's a good chance that the pings would have been deemed inadmissible altogether.



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I didnt really get the point in the episode about the Leakin Park pings. You say they dont match the testimony because Jay says he is at the burial site, while the Closing Arguments say he is driving up to the site. Seems close enough. Whats the inconsistency?

Posted by: anon | Jul 28, 2015 2:28:02 PM

There has been a ton of work done in search and rescue on tracing location from cell phone pings. No one in their right minds would find cell phone pings admissible evidence of ANYTHING. It is even possible to get "false pings" that is pings which show that the cell phone connected to the tower when it really didn't.


Is on example of S&R folks using cell phone pings to track locations. The whole case beyond this one link is fascinating on this topic.

Posted by: Daniel | Jul 28, 2015 2:28:48 PM

Can this new information be used in the appeal for Adnan's case?

Posted by: Penny | Jul 28, 2015 3:01:35 PM

anon: That's kind of the point, though. Pings at best give you a general idea of the broad geographic range in which the phone was located during a call. It can't do more, if it can even do that.

Daniel: Good points.

Penny: Unfortunately, no.

Smhwl: Only if bad faith can be proven.

Posted by: Colin Miller | Jul 28, 2015 4:36:40 PM

I don't fully follow why the tower evidence would be wholesale inadmissible under Frye. It seems to have general acceptance as a method of ascertaining someone's general whereabouts (or at least where they aren't, Guam...). I know that borders on a relevance issue, but that seems to be a relevance issue, not Frye. So couldn't the prosecution have it admitted generally for broad location evidence? Then the defense is free to attack reliability statements by ATT.

Posted by: Joel | Jul 28, 2015 5:51:17 PM

On what basis do you conclude that this was the first case involving cell tower pings in MD?

Wouldn't the State have called AW at any Frye/Reed hearing and if he could explain that an incoming call could be reliable if made close in time to another incoming call pinging the same tower, wouldn't that have been more compelling than a fax cover sheet written by in house counsel for a business?

Posted by: Jane | Jul 28, 2015 7:16:04 PM

Great work professor! You have stunned the experts with your technical knowledge and skills. Keep the ideas coming! You could make a second career in that field.

Posted by: M Cooper | Jul 29, 2015 1:33:46 AM

Why couldn't the failure to ask for a Frye Hearing be grounds for an Ineffective Assistance of Counsel appeal?

Is it because this issue wasn't raised in an earlier direct appeal and is therefore time barred or is it because it was belated raised by Gutierrez during trial and rejected?

Posted by: Alex | Jul 29, 2015 1:54:39 AM

Joel: As we noted, AT&T’s cover sheet stated that incoming calls were not reliable for determining location. Therefore, under Frye, they wouldn’t be admissible. As for outgoing calls, we described some of the flaws in the way that the testing was done. That would go to reliability, not relevance. I’m not sure whether evidence of the outgoing call pings would have been deemed inadmissible, but none of the pings actually helped the State’s case in a meaningful way.

Jane: Sarah said it on Serial, and we weren’t able to find any prior precedent on the issue. Moreover, under Frye, could be reliable isn’t good enough. Also, I don’t think that AW would have said that back-to-back calls are sufficiently reliable. For example, both of those calls could have come from the same person who lived close to Leakin Park based on the quirk with AT&T.

M Cooper: I’m glad that we’ve consulted actual experts for the cell phone and autopsy episodes. I’m good at analyzing the legal issues raised by what our experts have found, but I’d never claim to have expert knowledge myself.

Alex: Right. It’s too late to raise these issues now.

Posted by: Colin Miller | Jul 29, 2015 3:03:30 AM

Colin, so in all probability, you could say that Adnan's phone was in the vicinity of Leakin Park? His phone pinged tower L689b twice that evening which mainly covers the park.
Undisclosed have Adnan's full cell phone records for approximately the 45 days that following the 13th of January, but Rabia does not want to release them.
If you take the view that the L689b pings are just random and Adnan wasn't within Leakin Park, then in all probability I would imagine you would find that Adnan would ping the L689b tower many times over the 45 days following the 13th Jan, because after all the 13th was just a NORMAL day for Adnan.
Colin, are you able to answer for us how many times Adnan pings tower L689b from the 13th Jan until his arrest?

Posted by: Ben | Jul 29, 2015 4:05:00 AM

Ben: Given the AT&T cover sheet and what we’ve learned about incoming calls, I don’t think that the 7:09 and 7:16 P.M. calls on January 13th tell us anything meaningful about the location of Adnan’s phone. Given this, I haven’t tallied up the number of times his phone pinged the towers that were adjacent to Leakin Park in the ensuing weeks. That said, Susan mentioned an occasion on which Adnan’s phone pinged another tower adjacent to Leakin Park during a track meet, and I believe that she posted about another occasion on which Adnan’s phone pinged a tower adjacent to Leakin Park (possibly L689b).

Posted by: Colin Miller | Jul 29, 2015 6:11:23 AM

Thanks for the clarification! One follow up, would AT&Ts statements regarding reliability of location data from incoming calls make the full technology per se inadmissible under Frye (I.e lacking general acceptance)? It seems like the technology does have acceptance for certain purposes, albeit unreliable in others.

With breathalyzers there are extremely unreliable situations, like poor calibration or if the defendant had had a drink shortly before the test was administered. Those are things the defense is free to attack on cross, but don't render the full technology per se inadmissible.

There does seem to be limited value to the prosecution if the tower data is discredited for incoming call location, but that would not seem to be a Frye issue.


Posted by: Joel | Jul 29, 2015 6:34:02 AM

Colin, thanks for your answer. The reason I asked was that most decisions of the intermediate appellate court (especially criminal appeals) are unreported and would not show up in a Westlaw/Lexis search and the highest court doesn't grant cert in many cases, so it would seem that this may not have been a new issue in the trial courts and may very well have been deemed reliable.

I agree that could be reliable isn't good enough, but I sincerely doubt that that "quirk" with AT&T would have been known to those involved in this case (could be wrong) and absent that quirk, incomings back to back are reliable for cell site location.

Posted by: Jane | Jul 29, 2015 6:37:28 AM

Joel: AT&T’s statements wouldn’t make the full technology inadmissible, just the incoming calls. The rest of the evidence might have been admissible, but it was really only the 7:09 and 7:16 pings that mattered.

Jane: Yes, there could have been unreported prior opinions, but those would have been non-precedential. In other words, a Frye hearing would have been fully warranted.

Posted by: Colin Miller | Jul 29, 2015 7:22:43 AM

Ok, I just think it is misleading to state: "given that Adnan's case was the first one involving cell tower pings in Maryland, and given the odd way in which the testing was done, I think there's a good chance that the pings would have been deemed inadmissible altogether" when it is highly possible this issue had come up many times in the trial court and had been admitted previously. You could say, "given there were no reported appellate opinions addressing the admissibility of cell site evidence," and that would seem to better explain it.

Also, one question I keep coming back to (and I don't know the answer) is whether this is really new science at all or just extrapolating existing RF engineering science to a new device. Seems like that would make a big difference.

Posted by: Jane | Jul 29, 2015 8:14:05 AM

Thanks professor,
Yes, it was very obvious to every listener that that expert had a very deep personal knowledge about the system in question, and was a leading expert on how to localize objects, including persons, with the help of radio waves.

Posted by: Martin Cooper | Jul 29, 2015 9:59:48 AM

why won't Rabia release his cell records from Jan 14th to the date of his arrest? Is it a request by his lawyer that she not release those? They could go a long way in showing that the 13th was just another normal day if his cell pinged any of those towers in Leakin Park. I agree that the 7 o'clock timeframe is out the door, but I definitely am not convinced, by any measure, that Adnan is innocent.

Speaking of which, Colin, in your opinion, what evidence have you come across so far that convinces you that Adnan is innocent? Or are you not yet convinced and merely think he got a raw deal in court (which I would agree with)?

Much as I want to believe Adnan is innocent, I'm nowhere close to that feeling yet.

I am very eager to see what the DNA evidence brings up, but even so, Jay complicates everything regardless of how many times he's changed his story.


Posted by: Jake | Jul 29, 2015 10:25:44 AM

While the location of 7:09 and 7:16 pm may not be reliable, why is Adnan calling Jenn's pager at 7:00 pm, 8:04 pm and 8:05 pm? Did he not claim to be in the mosque at that time?

Posted by: S | Jul 29, 2015 12:39:27 PM

Let me answer Jane's question about RF reliability. In order to understand the issue we need to consider the context of the use to which the data is put. For example, wireless location data is best understood statistically--we can pinpoint a radius with a degree of confidence. "Degree of confidence" understood in its statistical sense and a radius meaning a physical space whose limits vary. A great example of this is the current hunt for the missing Malaysian airplane. That entire hunt is being guided by nothing but ping data because satellites use the same basic methods and face the same basic issues as all RF transmissions. We all know how well that hunt is going.

So take E911 data. With E911 there are lots of false positives. This is because when it comes to emergency services we error on the side of caution. It's better to send someone out there to look even if we can't locate the cell phone then not look and risk losing a life.

When we talk about DNA we have very high levels of statistical confidence on the range on one in a billion. But with wifi we don't have that same level of confidence. What we can say is that there is a 90% probability that a person was within X distance from point A. But this means, contrary to the statement made by the poster above, that there is a small but very real risk that the cell phone was in fact in Guam. Cell phones, and RF transmission equipment in general, were not designed with the idea that their data was to be used in the court of law--they were designed for communication purposes. The law is trying to piggyback.

So the question becomes just how reliable do these type of statistics have to be to satisfy a legal test? My own view is that there is a tendency for people to find unjustified confidence in math. So testimony that is allowed simply becomes the ipse dixit of an expert.

Posted by: Daniel | Jul 29, 2015 2:13:13 PM

You guys mentioned several times that when the prosecution was doing the testing on the tower pings that they never got out of their car at any point, I'm curious as to how you know this?

Posted by: Riley | Jul 30, 2015 6:18:33 AM

Ben, wether those 7:09 and 7:16 calls were made from Leakin Park or not, matters very little in fact, because autopsy has her not on her right side in a shallow grave at 7:09 anyway.

Posted by: Liz | Jul 30, 2015 7:00:33 AM

Adnan calling Jenn's pager at the times he "claimed" to have been at the mosque is consistent with the fact that a mosque is very different from a church. You don't have to be inside the whole time, and you have the freedom to get up and leave the room whenever you choose. Rabia pointed out that if you've ever been in a mosque or know about mosque's, it's general knowledge that this is totally normal and not suspicious at all. That's just how mosque's operate --people walk in and out as they please.

Posted by: Shar | Jul 30, 2015 10:18:56 AM

So what reason does adnan have to call Jen during religious services if they weren't that close?

Posted by: Robyn | Jul 30, 2015 6:15:04 PM