There is no precedent for the legislative branch to subpoena a former President of the United States, the executive branch. No court, including the Supreme Court, would validate a congressional subpoena against the President. The separation of powers would not permit the enforcement mechanism and there is no constitutional authority within the legislative branch to compel the executive. Period.
As a result, the effort of the J6 committee is essentially a made for television performance intended to create some goofy October surprise in advance of the November midterm election. The transparency of the insufferable political nonsense is clear. President Trump responded via Truth Social:
As even Politico admits, “There is little precedent for such a move against a former president, which would raise thorny separation of powers issues that have rarely, if ever, been litigated. Only one former president has ever been subpoenaed by Congress — Harry Truman in 1953 — and he defied the summons, contending it would set a dangerous separation-of powers precedent.”
The committee will likely create some ridiculous multi hundred-page report, created under the auspices of some authority they have manufactured out of thin air. The entire enterprise has been a massive waste of taxpayer funds as the baseline for the committee itself is nothing more than a partisan election effort.
Even die-hard democrats acknowledge the pantomime is a grand waste of time.