Last week a federal judge in the District of Columbia indicated he intended to rule that the House of Representatives lacked legal standing to sue the Trump administration over Trump's declaration that he would be diverting already-allocated government funds to build a border wall under the pretense of a "national emergency." U.S. District Judge Trevor McFadden said that Congress had other means of accomplishing the same goal—for example, passing legislation forbidding it.
On Monday, the House indicated that it will be appealing the D.C. decision. The Washington Post reported that “The House on Monday gave notice of its plans to U.S. District Judge Trevor N. McFadden of Washington, six days after the judge said he would toss out the House case, finding that one chamber of Congress lacks legal standing to sue the president.”
The D.C. decision conflicts with a previous ruling by a different federal judge, this one based in California, who not only allowed a similarly premised suit by outside advocacy groups to proceed but also issued a temporary halt to the wall spending while the case moved forward. The Trump administration is appealing that decision; the House is appealing the decision in D.C.
The short version is that we can expect this to work through the appeals courts fairly quickly, and the odds that it will end up before the Supreme Court itself appear to be high. It will be interesting to see how the court's hard-right advocates for "limited" government power hash out a reasoning for why a conservative president can flat-out reappropriate money designated by Congress for one purpose for another, unbudgeted priority of the president's own choosing.