A few recent revelations that may be of interest to those carrying cellphones while operating:
First, Chameleon Associates comments here on Textalyzer, a device to determine texting activity during vehicle accidents. "The device shows if the user was in hands-on or hands-free mode, and what on the phone was being tapped or clicked. Similar to a breathalyzer, this new devise (looks like an i-pad) would be used by law enforcement after an accident or event to determine if a driver had been on their phone." The NYT wrote about this last year too.
Forensics of phone exterior
Second, Mary Griggs at Popular Science writes about residue on the exterior of cellphones and profiling information gained from forensic analysis. Her piece is a summary of a study titled "Lifestyle chemistries from phones for individual profiling," published at PNAS.
The chemical analysis of materials on the phone could reveal, singly and in combination, many profiling traits about the user. One thing to mention is the term "signatures" used by the chemists versus law enforcement and intelligence professionals. The distinction between signatures and profiles is important. Signatures identify a particular individual, such as fingerprints, DNA, facial recognition, gait recognition, ear outlines, iris scans, and voice recognition. In another line of inquiry, profiling information is circumstantial evidence to help profile a suspect. Residue such as lotions, food particles, explosive residue, and other "gunk" left on a phone leads to inter-deductions about character, fitness, age and gender, lifestyle traits, and overall behavior.
This raises an interesting right to privacy issue for search incident to arrest. The Supreme Court ruled in 2014 that the Fourth Amendment protects citizens from unreasonable searches of electronic data on cellphones after arrest. Police need a warrant for this. What about searching the exterior profiling "chemical data"? Another issue arises at checkpoints where the Fourth Amendment protections are relaxed and at checkpoints abroad. As the chemical tech advances in speed and depth of results, this may become more concerning.
Quickly thinking of some counter-measures, just as one might carry lens cleaning and alcohol wipes for cleaning objects before discarding, the same applies to cellphones. If one uses burner phones, wiping for prints might not be enough. Wipe for the residual gunk too. Wipe before entering checkpoints, wipe and handle with gloves before expected detainment. And so on.