Why would Donald Trump be arrested?

Question

The New York Times writes:

Donald J. Trump is preparing to walk into a Manhattan courtroom as both a defendant and a candidate, making final plans for his arrest on Tuesday [...].

Why would he be arrested? Is there a danger of flight? That seems implausible, given that he has arranged his appearance in front of the court out of his own volition, and because of his commercial, family and real estate ties to the country, and his plans to run for president again.

Is there a danger of destroying evidence? In all reality, that would have happened by now, and most relevant searches have probably been conducted already.

What other reasons would be there for an arrest?

As a clarification: If I'm not mistaken, in Germany an indictment would simply be delivered by special registered mail, unless one of the above-mentioned dangers was present.

In the U.S., a simple delivery of an indictment can take on an appearance which I can only perceive as unnecessarily disparaging. A defendant is presumed innocent unless proven guilty. To me this principle implies that defendants should be treated with respect like any other citizen. Putting them in humiliating situations, let alone using force like restraining them with handcuffs like in the case of Mr. Weisselberg contradicts this principle, unless there is reason to believe they would flee or otherwise obstruct the trial.

Answer 1

An accused would be arrested for the purposes of arraignment ("even a scheduled arrest is still an arrest"). That does not entail that the accused would be held in custody pending or during trial. Many commenters are of the view that Mr. Trump would be released under his own recognizance without bail.

Reference: AP News.

Answer 2

New York Criminal Procedure Law, section 210.10, Requirement of and methods of securing defendant's appearance for arraignment upon indictment, subsection 3 (emphasis added):

3. If the defendant has not previously been held by a local criminal court for the action of the grand jury and the filing of the indictment constituted the commencement of the criminal action, the superior court must order the indictment to be filed as a sealed instrument until the defendant is produced or appears for arraignment, and must issue a superior court warrant of arrest. Upon the request of the district attorney, in lieu of a superior court warrant of arrest, the court may issue a summons if it is satisfied that the defendant will respond thereto. Upon the request of the district attorney, in lieu of a warrant of arrest or summons, the court may instead authorize the district attorney to direct the defendant to appear for arraignment on a designated date if it is satisfied that the defendant will so appear. A superior court warrant of arrest is executable anywhere in the state. Such warrant may be addressed to any police officer whose geographical area of employment embraces either the place where the offense charged was allegedly committed or the locality of the court by which the warrant is issued. It must be executed in the same manner as an ordinary warrant of arrest, as provided in section 120.80, and following the arrest the executing police officer must without unnecessary delay perform all recording, fingerprinting, photographing and other preliminary police duties required in the particular case, and bring the defendant before the superior court. If such superior court is not available, the executing police officer may bring the defendant to the local correctional facility of the county in which such superior court sits, to be detained there until not later than the commencement of the next session of such court occurring on the next business day.

So, the district attorney can ask the court not to issue a warrant, but the court isn't obliged to comply. In fact the court is obliged not to comply if it concludes that the defendant may not appear voluntarily or in response to a summons.

My guess is that the district attorney did not make the necessary request. However, as noted in the AP article linked in Jen's answer, "Manhattan District Attorney Alvin Bragg’s office said it had contacted Trump’s lawyer to coordinate his surrender and arraignment," so it's entirely possible that the third option is in play, in which case Trump won't necessarily be arrested.