The fence is ineffective at carrying out its stated goals.  Not all illegal immigrants who are in the United States arrive by means of crossing the border; some overstay legally-acquired work visas. Attempts to implement "virtual" components of the fence have failed on several grounds. Images were too blurry, the systems performed poorly in bad weather, and there were false detections because of the inability to distinguish between animals and people.1 The technology also suffered from software bugs, and ultimately squandered billions of dollars.2 Because not all of the approximately 2000 mile border is covered by actual fencing, and even the physical fencing that exists is not continuous and relied on virtual components to cover the gaps, immigrants can easily go around the fence or through the weak points.3 In the past, immigrants have also used ladders or deception techniques (like cars with hollowed out dashboards) to bypass the fence. Additionally, drug runners have developed extensive and sophisticated tunnels to duck the wall and clear any sort of security checkpoints, rendering this defense mechanism with a price tag in the billions of USD4 (and expensive upkeep costs to boot) virtually useless.5 Finally, many individuals who cross the border looking for employment do so repeatedly, even when they are deported or turned back at the border by agents.6 In jurisdictions where these individuals are held in detention on misdemeanour charges, they contribute to overcrowding in prison facilities and consume valuable prosecutorial resources.7  1Ryan, Jason. "Homeland Security Axes Bush-Era 'Virtual Fence' Project."  2NYT Editors. "Virtual Failure on the Border."  3The Economist. "Good neighbours make fences." 4McFadyen, Jennifer. "Immigration Issues: US-Mexico Border Fence Pros and Cons."  5Global Security. "US-Mexico Border Fence."  6Federation for American Immigration Reform. "US Mexico Border Fence and Patrol Operations."  7Archibold, Randal and Preston, Julia. "Homeland Security Stands by Its Fence."