You don’t absolutely need a rear-facing dash cam, or any dash cam for that matter. However, if you want to catch detailed footage of any accidents you will need them. Since getting rear-ended by drivers not paying attention is possible, a rear-facing dash cam is quite beneficial. However, some people are not as interested in them as front-facing dash cams due to license plates always being in the. Note that some states, such as Maryland, require front and rear license plates and therefore get the most out of rear-facing dash cams.