Legal Opinion on Emergency Declaration by Trump

The thing about the emergency declaration by the president in order to fund the border wall is that a judicial check on him by the Supreme Court is extremely doubtful. There will likely be an injunction from the 9th circuit, but with 5 conservative justices (unless you consider Chief Justice Roberts a swing vote) the case would definitely be brought to the Supreme Court since a writ of certiorari only requires 4 justices. The reason that the SCOTUS is likely to strike down any injunctions against his action is because traditionally the SCOTUS opines that situations with these elements are "political questions" and that the courts do not have the authority to rule on these issues.

The only viable method that could end the emergency and take away trumps ability to spend for the border wall is a rebuke from congress. It is highly likely that such a measure will pass the House of Representatives. However, it is doubtful such a measure will pass McConnell's Senate. Remember, the Senate Majority Leader has the sole authority to set the calendar. Mitch McConnell can simply choose not to cause a vote in the Senate (which is a tool he has used from the beginning of his leadership role).

All in all, the wall will probably begin being built soon and he may even have time to complete it depending on his ability to secure continuing funding, also assuming he wins in 2020.