Wisconsin and all other states allow breathalyzers to test drivers and see if they have consumed alcohol before or during driving. State laws include something called "implied consent." This means when a person gets a license, they agree to consent to a breath test under certain circumstances.
No state currently has an implied consent law for textalyzers but New York is trying to pass one. According to an article in ars technica:
"The roadside technology is being developed by Cellebrite, the Israeli firm that many believe assisted the Federal Bureau of Investigation in cracking the iPhone at the center of a heated decryption battle with Apple.
Under the first-of-its-kind legislation proposed in New York, drivers involved in accidents would have to submit their phone to roadside testing from a textalyzer to determine whether the driver was using a mobile phone ahead of a crash. In a bid to get around the Fourth Amendment right to privacy, the textalyzer allegedly would keep conversations, contacts, numbers, photos, and application data private. It will solely say whether the phone was in use prior to a motor-vehicle mishap.
Further analysis, which might require a warrant, could be necessary to determine whether such usage was via hands-free dashboard technology and to confirm the original finding.
The legislation was prompted by intense lobbying from the group Distracted Operators Risk Casualties (DORCs). The son of its co-founder, Ben Lieberman, was killed in 2011 by a distracted driver in New York. The proposed law has been dubbed "Evan's Law" in memory of 19-year-old Evan Lieberman.
"When people were held accountable for drunk driving, that's when positive change occurred," Lieberman said in a press release.
"It's time to recognize that distracted driving is a similar impairment, and should be dealt with in a similar fashion. This is a way to address people who are causing damage."
Currently when a driver hits a bicyclist the police might try to look at the person's phone. However, if the bicyclist thinks the person was texting or on the phone at the time of the crash the bicyclist will have many hurdles to jump to try to prove this.
Further, although police may look at a phone to see text messages, there is no way to tell whether the person was reading an incoming text which would be just as dangerous as sending a text. Finally, people could be emailing, reading emails, looking at facebook etc. and there is no way for police to tell this just by looking at a person's phone.