L to R- Abbe Lowell, Senator Robert Menendez, unidentified woman, outside the Federal Courthouse in Newark, NJ. Robert Menendez has been indicted on bribery charges. Carmen Natale

As jurors in the corruption trial of U.S. Sen. Bob Menendez, D-New Jersey, heard on Wednesday about flights Menendez took at the expense of co-defendant Salomon Melgen, the proceedings returned to a central theme in the case: the two men’s friendship and its relevance as a defense to bribery charges.

FBI agent Alan Mohl testified about roughly 20 flights the senator took to the Dominican Republic between the years 2006 and 2013, the period covered in the indictment, either on Melgen’s own plane or on commercial flights paid for by Melgen. Responding to questions from the government, Mohl testified that none of the flights was listed on Menendez’s gift disclosure forms, nor were upscale lodgings the senator enjoyed in Paris and the Dominican Republic at Melgen’s expense.

But Menendez’s lawyer, Abbe Lowell, got heavy resistance from U.S. District Judge William Walls when he sought to present evidence of earlier trips the senator took to the Dominican Republic, beginning in 1998, at his own expense. After the judge excused the jury from the courtroom, Lowell asked, “What kind of bribe is it when you have to pay to get to your friend’s house?”

Walls initially refused to permit questioning of Mohl on Menendez’s travels to the Dominican Republic before 2006.

“The purpose of the indictment is to limit the time under consideration,” Walls said.

Lowell said the long duration of Menendez’s friendship with Melgen was “a central argument of the defense,” but Walls replied, “friendship can be changed, it can be colored and contaminated by corruption. It can serve as the camouflage for corruption.”

After Assistant U.S. Attorney Monique Abrishami said that defense representations about Menendez’s flights to the Dominican Republic did not mean that he was there to visit Melgen, Lowell represented that the senator was staying at Melgen’s home during the pre-2006 visits to that nation. Walls then said he would permit limited questioning of the FBI agent about the senator’s flights to the Dominican Republic before 2006, and the jury returned to the courtroom.

Lowell then proceeded to examine Menendez’s passport in order to detail to the jury eight times that the senator flew to the Dominican Republic on his own expense between 1998 and 2006. Most of those trips were in the month of August, when Melgen celebrates his birthday, Lowell said.

Earlier on Wednesday, jurors saw a video clip from CNN in which reporter Dana Bash questioned Menendez about his failure to list flights and lodgings from Melgen on his Senate disclosure form and why he reimbursed Melgen to the tune of $58,500 for two flights after the fact. Menendez told the reporter his reporting requirements “unfortunately fell though the cracks,” adding that he had a busy travel schedule due to his leadership post in the Democratic Congressional Campaign Committee. The jury also saw a redacted version of a 2013 press release issued by the senator’s office that claimed he only accepted three flights from Melgen. Both the video and the press release were edited to remove the senator’s responses to allegations by conservative bloggers that he used prostitutes while in the Dominican Republic, including some who were underage.

Walls ruled on Tuesday that the press release and video could be presented to the jury after references to the prostitution allegations were edited out.

Abrishami questioned Mohl at length about whether the flights Menendez received from Melgen met the various exemptions to senators’ gift-reporting obligations, and he answered in the negative in each case. Lowell, on cross-examination, asked Mohl to point out before the jury that the Senate rules for gift reporting require violations to be made “knowingly and willfully.”

Menendez and Melgen are on trial on charges that the senator accepted free lodgings and flights and campaign contributions from the Florida eye doctor in exchange for the senator’s intervention with federal officials to aid Melgen’s business matters and to help three of Melgen’s foreign-born girlfriends get U.S. visas. The trial is expected to last until the Thanksgiving holiday.