Federal law authorizes the Department of Homeland Security (DHS) to construct barriers along the U.S. borders to deter illegal crossings. DHS is also required to construct reinforced fencing along at least 700 miles of the land border with Mexico, though fencing is not required to be deployed at any "particular location" alon g that border. Although congressional interest in the legal framework governing fence deployment has, in recent years, tended to focus on the stringency of the statutory mandate to deploy fencing along at least 700 miles of the southern border, attention has now shifted to those provisions in current law which allow, but do not require, the deployment of fencing and other barriers along additional portions of the U.S. land borders. Within days of taking office, President Donald J. Trump issued an executive order instructing the Secretary of Homeland Security, acting under existing legal authorities, to "take all appropriate steps to immediately plan, design, and construct a physical wall along the southern border ... to most effectively achieve complete operational control" of the U.S.-Mexico border. The order defines a "wall" to mean "a contiguous, physical wall or other similarly secure, contiguous, and impassable physical barrier." The order does not identify the contemplated mileage of the wall to be constructed. The primary statute authorizing DHS to deploy barriers along the international borders is Section 102 of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA). Congress made significant amendments to IIRIRA Section 102 through three enactments—the REAL ID Act of 2005, the Secure Fence Act of 2006, and the Consolidated Appropriations Act, 2008. These amendments established a mandate upon DHS to construct hundreds of miles of new fencing along the U.S.-Mexico border, and also provided the Secretary of Homeland Security with broad authority to waive "all legal requirements" that may impede construction of barriers and roads under IIRIRA Section 102. These statutory modifications, along with increased funding for border projects, resulted in the deployment of several hundred miles of fencing and other barriers along the southwest land border between 2005 and 2011. However, it appears that further fencing would need to be deployed in order for DHS to satisfy the statutory requirement that the agency construct fencing "along not less than 700 miles of the southwest border." DHS's policy not to deploy a substantial amount of additional fencing, beyond what is expressly required by law, appeared to be premised primarily on policy considerations and funding constraints, rather than significant legal impediments. Indeed, nothing in current statute would appear to bar DHS from installing hundreds of miles of additional physical barriers along the U.S.-Mexico border, even beyond the 700 miles required by law, so long as the action was determined appropriate to deter illegal crossings in areas of high illegal entry or was deemed warranted to achieve "operational control" of the southern border. Among other things, IIRIRA Section 102 in its current form
generally authorizes DHS to construct barriers and roads along the international borders in order to deter illegal crossings at locations of high illegal entry; requires the construction of reinforced fencing covering at least 700 miles along the southwest border, though the Secretary is not required to install fencing at any particular location; authorizes for the installation of additional physical barriers and infrastructure to gain operational control of the southwest border; requires a specified amount of fencing in priority areas along the southwest border, which DHS was instructed to have completed by December 31, 2008; and provides the Secretary of Homeland Security with authority to waive any legal requirements which may impede construction of barriers and roads under Section 102.
Federal law authorizes the Department of Homeland Security (DHS) to construct barriers along the U.S. borders to deter illegal crossings. DHS is also required to construct reinforced fencing along at least 700 miles of the land border with Mexico (a border that stretches 1,933 miles). Congress has not provided a deadline for DHS to meet this 700-mile requirement, and as of the date of this report, fencing would need to be deployed along nearly 50 additional miles to satisfy the 700-mile requirement. Nor has Congress provided guidelines regarding the specific characteristics of fencing or other physical barriers (e.g., their height or material composition) deployed along the border, beyond specifying that required fencing must be reinforced.
The primary statute authorizing the deployment of fencing and other barriers along the international borders is Section 102 of the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA; P.L. 104-208, div. C). Congress made significant amendments to IIRIRA Section 102 through three enactments—the REAL ID Act of 2005 (P.L. 109-13, div. B), the Secure Fence Act of 2006 (P.L. 109-367), and the Consolidated Appropriations Act, 2008 (P.L. 110-161, div. E). These amendments required DHS to construct hundreds of miles of new fencing along the U.S.-Mexico border, and they also gave the Secretary of DHS broad authority to waive "all legal requirements" that may impede construction of barriers and roads under IIRIRA Section 102. These statutory modifications, along with increased funding for border projects, resulted in the deployment of several hundred miles of new barriers along the southwest border between 2005 and 2011. But in the years following, DHS largely stopped deploying additional fencing, as the agency altered its enforcement strategy in a manner that places less priority upon barrier construction.
On January 25, 2017, President Donald J. Trump issued an executive order that, among other things, instructs the Secretary of Homeland Security to "take all appropriate steps to immediately plan, design, and construct a physical wall along the southern border ... to most effectively achieve complete operational control" of the U.S.-Mexico border. The order defines a "wall" to mean "a contiguous, physical wall or other similarly secure, contiguous, and impassable physical barrier." The order does not identify the contemplated mileage of the wall to be constructed.
Until recently, interest in the framework governing the deployment of barriers along the international border typically focused on the stringency of the statutory mandate to deploy fencing along at least 700 miles of the U.S.-Mexico border. But attention has now shifted to those provisions of law that permit deployment of fencing or other physical barriers along additional mileage. IIRIRA Section 102 authorizes DHS to construct additional fencing or other barriers along the U.S. land borders beyond the 700 miles specified in statute. Indeed, nothing in current law would appear to bar DHS from installing hundreds of miles of additional physical barriers, at least so long as this action was determined appropriate to deter illegal crossings in areas of high illegal entry or was deemed warranted to achieve "operational control" of the southern border. DHS's policy not to deploy a substantial amount of additional fencing, beyond what is expressly required by law, appeared primarily premised on policy considerations and funding constraints, rather than significant legal impediments.
This report discusses the statutory framework governing the deployment of fencing and other barriers along the U.S. international borders. For more extensive discussion of ongoing activities and operations along the border between ports of entry, see CRS Report R42138, Border Security: Immigration Enforcement Between Ports of Entry, by [author name scrubbed].