The supreme court has ruled that a Manhattan grand jury may have access to some of Donald Trump’s financial documents, dealing a major blow to the president in his fight to keep his tax records secret – although the records were not expected to become public ahead of the November election. Prosecutors in New York had sought the documents as part of an investigation into whether Trump had improperly handled hush payments, including one to the pornographic film actor star Stormy Daniels during the 2016 presidential campaign. “This is a tremendous victory for our nation’s system of justice and its founding principle that no one – not even a president – is above the law,” Cy Vance Jr, the Manhattan district attorney, said. “Our investigation, which was delayed for almost a year by this lawsuit, will resume, guided as always by the grand jury’s solemn obligation to follow the law and the facts, wherever they may lead.” Legal analysts warned, however, that the subpoena issued by Vance was not likely to be enforced anytime soon, and said Trump’s tax records were not likely to become public in the near future, under grand jury secrecy rules. The records could come to light if Trump is charged with a crime after he leaves office. Trump won a temporary reprieve in a separate fight over his financial records, in which multiple Democratic-led committees in Congress had sought documents for investigations including an ethics investigation and one into foreign influence in the 2016 election. The court affirmed both that Congress had the power to subpoena the documents and that the president had some privilege not to turn them over, and ordered a lower court to reconsider the “significant separation of powers concerns implicated by congressional subpoenas for the president’s information”. Trump reacted angrily on Twitter. “This is all a political prosecution,” he wrote, referring to the investigation of special counsel Robert Mueller. “I won the Mueller Witch Hunt, and others, and now I have to keep fighting in a politically corrupt New York. Not fair to this Presidency or Administration!” Justice department lawyers in that case argued that Congress had not demonstrated a legislative purpose for the request and that such a request for a president’s personal documents amounted to “harassment”. Justices on the court’s liberal wing challenged both assertions during oral arguments, with Ruth Bader Ginsburg pointing out that the request by Congress for Trump’s tax records was unprecedented only because Trump’s flat refusal to release his tax records was unprecedented. The speaker and senior Democrat, Nancy Pelosi, said the House of Representatives would continue its legal efforts to obtain Trump’s financial records. “A careful reading of the supreme court rulings related to the president’s financial records is not good news for President Trump,” Pelosi said in a statement. Gillian Metzger, professor of constitutional law at Columbia University, said before the rulings were handed down that it would be “very concerning” if the court failed to support the congressional subpeonas. “Our system of separation of powers requires that Congress be able to exercise its powers, and to do that it has to be able to get information and to undertake oversight of the executive,” she said. Alongside other major rulings in this court term, the tax records decisions offered a glimpse of how a new conservative majority on the court, installed under Trump, could shape public life for decades to come. Trump was represented in the Manhattan case by Jay Sekulow, who was also a lead lawyer for Trump during the impeachment hearings. Sekulow advanced an expansive argument for executive power, asserting that sitting presidents are immune from criminal investigation. “We are pleased that in the decisions issued today,” Sekulow said in a statement, “the supreme court has temporarily blocked both Congress and New York prosecutors from obtaining the president’s financial records. We will now proceed to raise additional constitutional and legal issues in the lower courts.” While the rulings did not result in an immediate handover of documents, Sekulow’s characterization of the court having “blocked” the records was seen as misleading, with the justices explicitly rejecting his argument that such records were off-limits. In oral arguments in May, both Trump appointees on the court, Neil Gorsuch and Brett Kavanaugh, seemed to coax Sekulow, without success, toward a more limited argument. Lawyers for the prosecution responded that the president must comply with the law. The congressional subpoena for Trump’s tax records from one of his accountants, Mazars USA, set up a broader separation-of-powers clash. The House intelligence committee sought the documents as part of its investigation of foreign influence in the 2016 election, while the oversight and reform committee said it was considering rewriting ethics laws to require elected officials to disclose tax documents. Trump lawyer Patrick Strawbridge argued that “these types of subpoenas are going to be uniquely troublesome and burdensome” and said: “Congress lacks any power to inquire into the private affairs of any individual.” In response, a lawyer for the House of Representatives, Douglas Letter, pointed out that Richard Nixon had supplied the Watergate tapes in response to a congressional subpoena, and that Bill Clinton sat for a deposition, while in office, in the Paula Jones sexual harassment case. “History really matters here,” Letter said, “and it shows you that the arguments here made by Mr Trump ignore an astonishing amount of history”. Trump’s lawyers said the “evidentiary demands” advanced by Congress were burdensome, and that Trump was being distracted by having to bring a lawsuit to stop his accountants from turning information over to Congress. “There’s no way that this could interfere with the president,” Letter replied in oral arguments, “because he doesn’t have to do anything. This is a subpoena to two banks and an accounting firm.” Joan E Greve contributed reporting