TODAY | April 18, 2013
>>> attack has revived a long time debate about surveillance cameras in cities and towns. they may hold the key to solving that case. and now some are calling for even more to be put in place across the country. but others worry about privacy. nbc's tom costello joins us once again. tom?
>> hi there, matt. security cameras are, of course, everywhere. they're used to watch stores, banks, homes, stadiums and downtown streets. increasingly, big brother really is watching. it's the first question police and the media always ask, is there video? fires, armed robberies , police chases, petty street crimes , fights on school buses . the boston attack itself all caught on cam. nationwide, more than 30 million surveillance cameras have been installed in the past decade alone. now, a leading republican says the u.s. needs to install more cameras to catch criminals and deter terrorists.
>> being out in the street is not an expectation of privacy. anyone can look at you, see you, watch what you're doing.
>> but privacy advocates aren't buying it.
>> do we want to live in a society where every single thing we do is monitored all the time. monitored and judged and assessed and recorded.
>> 3,000 are trained on new york's lower manhattan . chicago hope new cameras there will help cut into the rising murder rate. while in los angeles , the cameras are part of a sophisticated system. calls for help, even social media .
>> sometimes you're going to see the police and sometimes you won't, but it doesn't mean we're not working hard to protect the people.
>> reporter: great britain has among the most cameras. one for every 32 people. but in this country, civil libertarians worry what the government might do with all of those photos and video.
>> do we take all the video and funnel it to the national security agency for them to monitor for terrorism for law enforcement for drug enforcement or parking violations?
>> think about this, face recognition software is here now. so should the government be allowed to have a data base and track your every move based on where you pass by different cameras? should stores e-mail you with offers when their cameras catch you walking by? you can imagine the courts will have to eventually weigh in on this in some fashion.