Could Polanski sue former DA Ted Wells, the estate of the Judge, the L.A. District Attorney's office and the Superior Court of Los Angeles in a federal civil action for the violation of his constitutional right to due process of law and a fair sentencing proceeding, and have the illegality of their actions determined while he's in Switzerland?

The problem for Polanski filing such a suit is manifold. A few years back when I was defending prosecutors against civil suits such as the one you suggest, I had winnowed my defenses down to about 7, each of which was independently sufficient to get a dismissal right out of the box.

As to the judge:  he has absolute immunity - the "judicial immunity" - from civil suits for anything he does while in the judicial role.  This is an ancient immunity and has been reaffirmed within the last 20 years or so by the US S.Ct.

As to the prosecutor:  he has asbolute immunity - the "prosecutorial immunity" - from civil suits for anything he does while in the prosecutorial role, i.e., "as an advocate for the state".  You can look it up:  Imbler v. Pachtman, a US S.Ct. case from the late 60s, involving a man convicted of a murder he had not committed, by a California Court.  the prosecutorial immunity is before the S.Ct. again this term in the Pottowatomie [sp] County case out of Iowa - a prosecutor knowingly framed two guys for a murder (i.e., knowingly put in false evidence that pointed to them and away from his interests) and they both did over 25 years based on that framing.  I expect these former defendants will come away empty-handed.

All the lawyers and judges and support personnel get the benefit of the absolute judicial proceedings immunity, though the scope of that varies from state to state.  Anything said or done in the furtherance of judicial proceedings comes within that immunity.

Any claim Polanski would make would wind up being devolved to something called a malicious prosecution claim.  An essential element of that cause of action is that you are innocent of the crime you were prosecuted for and that they prosecuted you without probable cause.  This leads to two interesting problems.

First, if he was arrested pursuant to a judicial warrant (on a complaint or information), then to issue that there had been a judicial finding of probable cause.  So long as that finding (i.e., the arrest warrant) stands, he can't prove his civil case b/c there was probable cause.

Second, if he was indicted, that indictment is a finding by the grand jury that it is more likely than not that he committed the crime alleged, i.e., that there is probable cause.  Again, so long as the indictment stands, he can't prove his civil case.  

In federal civil cases where a plaintiff was alleging misconduct in a state criminal case, I used to combine these two principles (depending on which obtained in the particular case) with the Rooker-Feldman doctrine for a particularly nasty (as in lethal to the plaintiff's case) motion to dismiss.  Rooker-Feldman doctrine says, in so many words, that federal district courts do not review (or even question) the validity or content of duly entered state court decisions, nor do they sit as courts of appeal from decisions of state courts.  If the plaintiff wanted to get a civil case going, he would have to have had the warrant vacated and/or the indictment vacated in the state court, something (a) no one ever thinks about (they're much too happy just to get a dismissal) and (b) they would have been way out of time to do by the time they got around to realizing they needed to do it.  A couple years ago, the S.Ct really reined in the Rooker-Feldman doctrine (it was getting entirely too potent in a plethora of contexts), so I don't know whether it would work this way any more;  I haven't had any of those cases since that S.Ct. decision.

And then, finally there's another element to the malicious prosecution claim which any plaintiff has to prove:  that he was innocent of the crime charged.  It can't be a malicious prosecution if you were, actually or arguably, guilty.   The core problem with bringing a malicious prosecution claim for Polanski is that he has (at a minimum) indicated an intent to plead guilty or already has pleaded guilty to a crime.  To prove he was not guilty, he would have to admit that, when he said under oath that he was guilty, he was lying.  Problematic, at best.

If, on the other hand, no judgment in the criminal matter has been entered, then discovery is, of course, in order in the civil action.  That means, for example, that the plaintiff will have to give his deposition and answer written questions under oath - interrogatories.  There is a corollary rule which addresses this and which makes worse an already bad situation for the plaintiff:  when you sue, you waive your right to refuse to answer questions about the subject matter of the suit.  You sue someone for breaking your arm means you have to answer questions about your arm, how you use it, the treatment you receive, etc.

The problem with that rule for a plaintiff is that it has been interpreted through the decades in scads and scads of cases that this rule means a plaintiff must answer questions about the crime and any invocation of the Fifth Amendment to prevent or preclude questions along one line or another means he must accept his case being dismissed.

I once defended a prosecutor in a case where the plaintiffs were suspected of a murder, but were being held on forgery charges, and they argued they had been maliciously prosecuted by being improperly put under a very high bail because of the suspicion (but no charge) of the murder.    "Fine", I said.   "You say your clients are innocent of the murder and that supports their malicious prosecution claims against the prosecutor?"
"Yes", came the response from their lawyer.
"OK," I said.  "I'll take their depositions.  Since the prosecutor is a party, he has a right to be there and, as my client, can feed me all the questions I want to ask.  Because bringing and maintaining the suit is a waiver of the Fifth Amendment, your clients will have to answer them.  Under oath.  And, by the time I get done, they will both be looking at the business end of a needle."

That case went away within a week.

And, BTW, you see that with respect to all of these defenses, no one ever reaches the merits of the case.  

Then of course, the DA who now, after an interview for a documentary which he affirmed in multiple venues, is now asserting that he lied, with the only other witness dead.

Could Polanski sue former DA Ted Wells, the estate of the Judge, the L.A. District Attorney's office and the Superior Court of Los Angeles in a federal civil action for the violation of his constitutional right to due process of law and a fair sentencing proceeding, and have the illegality of their actions determined while he's in Switzerland?

which seems to already be answered. the real question, with respect to mr. polanski's case:

why hasn't he, in all this time, filed a civil suit, against those he claim committed acts which hurt him, while he was in europe?