Members of Congress who promise that money will be spent on efforts to secure the border conveniently withhold the fact that one Congress cannot bind a future Congress to appropriate funds mandated by already established laws. Such a practice is known as legislative entrenchment and courts have long upheld this position. If a future Congress does not want to appropriate funds to hire more border agents or build 700 miles of fencing, those lawmakers can opt not to appropriate funds for the effort.
Advocates of the Senate’s immigration bill point to different provisions in the bill that would ensure border security through the proposed Corker-Hoeven amendment. They claim $40 billion over ten years will be mandated to be spent on 700 miles of border fencing, 20,000 additional border agents and an immigrant-worker E-verify system, among other measures.
This issue is playing out with the new health-care law. The House of Representatives hold the purse strings to financing any program with tax-payer dollars and that is why there are repeated congressional threats to de-fund Obamacare.