John Dowd, President Trump's outside lawyer, outlined to me a new and highly controversial defense/theory in the Russia probe: A president cannot be guilty of obstruction of justice.

The "President cannot obstruct justice because he is the chief law enforcement officer under [the Constitution's Article II] and has every right to express his view of any case," Dowd claims.

Dowd says he drafted this weekend's Trump tweet that many thought strengthened the case for obstruction: The tweet suggested Trump knew Flynn had lied to the FBI when he was fired, raising new questions about the later firing of FBI Director James Comey.

• Dowd: "The tweet did not admit obstruction. That is an ignorant and arrogant assertion."

Why it matters: Trump's legal team is clearly setting the stage to say the president cannot be charged with any of the core crimes discussed in the Russia probe: collusion and obstruction. Presumably, you wouldn't preemptively make these arguments unless you felt there was a chance charges are coming.

• One top D.C. lawyer told me that obstruction is usually an ancillary charge rather than a principal one, such as aquid pro quo between the Trump campaign and Russians.
• But Dems will fight the Dowd theory. Bob Bauer, an NYU law professor and former White House counsel to President Obama, told me: "It is certainly possible for a president to obstruct justice. The case for immunity has its adherents, but they based their position largely on the consideration that a president subject to prosecution would be unable to perform the duties of the office, a result that they see as constitutionally intolerable."
• Remember: The Articles of Impeachment against Nixon began by saying he "obstructed, and impeded the administration of justice."

Bob Woodward tells me this "is a legal thicket and really has not been settled":

• "I think a president can only be reached through impeachment and removal. But the House and Senate could conclude a president had obstructed, and conclude that was a 'high crime.'"
• "In Watergate there was political exhaustion — plus, as Barry Goldwater said, 'too many lies and too many crimes.' These questions are now, in the end, probably up to the Republicans. The evidence was in Nixon's secret tapes. Is there such a path to proof now is one way or the other? We don't know."

Be smart: The one thing everyone agrees on is that the House of Representatives, with its impeachment power, alone decides what is cause for removal from office. For now, at least, the House is run by Republicans.

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