Not that it's relevant to the question of whether a defense attorney can do anything they want to in a court of law,
.....
Let me give you one example that happened to be the subject of a two-hour ABC 20/20 last week. In short, a woman tried to have her husband murdered. A friend she approached to do the deed went straight to the police, and they created an elaborate sting with an undercover cop posing as a contract hitter. When the case went to trial with overwhelming evidence, including videos from multiple angles of her making the deal, the defense claimed that she was auditioning for a reality TV show. No script, no producers, no contracts, no support; but she was allowed to make that claim. She was convicted and sentenced to 20 years.
The conviction was overturned on appeal, and at her second trial she skipped the reality tv defense and claimed that the police had entrapped into doing something she would never actually have done by sending her a "hitman." The result was a hung jury.
At her third trial, almost eight years after the crime, the defense made pretty much the same entrapment case, but the jury came back with a guilty verdict in 90 minutes. The defense is now appealing that conviction.
https://abcnews.go.com/US/dalia-dippolito-managing-prison-life-legal-teams-hope/story?id=70638556
That's one example of what the defense can do if they have enough time and money.
In another recent case (can't find a link at the moment), a man was convicted of kidnapping, raping and murdering a teen-age girl. DNA and other physical evidence identified him conclusively and exclusively. He claimed in court, supported by his lawyers, that he had had a secret relationship with her unknown to anybody else, that he had met her for consensual sex in the cold woods where her broken body was discovered, and that she was fine when he left her there because she wanted to be alone. He was convicted, too.
Defense attorneys are allowed to do pretty much anything they can to deflate overwhelming evidence against their clients. Judges don't want to be accused on appeal of impairing a defense. Pointing to a non-existent alternate suspect, calling witnesses liars and claiming police misconduct are basic tactics. In this case the lawyers are no doubt going to claim that Arbery was a dangerous criminal trying to escape, and the McMichaels were heroic citizens defending their community from a predator. And that's what the jury will be allowed to hear.