Amanda Bynes was arrested last night for marijuana possession (surprise!), reckless endangerment and felony evidence tampering when she threw a bong out of her New York City apartment window -- and it may be the best thing that's ever happened to her.

Sources say Bynes' family has been unable to get through to the erstwhile Nickelodeon starlet, who's expected to have a hearing sometime this morning.

Radar Online reports that Bynes' parents have been trying their darnedest to get a Britney Spears-style conservatorship for their troubled daughter, but that it probably won't happen.

"Rick and Lynn have met with several lawyers that handle conservatorships in the past month, because they want to get a conservatorship of their daughter," a source said. "They have been advised that even as disturbing as Amanda's behavior is, it's very unlikely that a judge would sign off on a temporary conservatorship."

The source added, "Conservatorships are very hard to get, and being mentally ill and addicted to drugs isn't enough. Amanda hasn't ever been to rehab or ever agreed to see a mental health professional. Her parents are absolutely powerless to do anything at this point."

One source said much of Bynes' behavioral issues come from her marijuana use, because it doesn't have the same effect on her as it does on, say, Snoop or Miley Cyrus, with an insider telling Radar, "It makes her more paranoid instead of mellowing her out."

A hearing for Bynes is expected today (video of her in booking is above), and the charges in general don't bode well for her -- she's still on probation for a September 2012 traffic violation.

While TMZ says it was a "building official" who called police because Amanda was toking up in her apartment building's lobby, someone else is claiming responsibility for alerting police to Bynes' antics and possible illness -- and he's speaking out, calling the move a "successful intervention."

Jonathan Jaxson -- who just a few weeks ago grabbed a bit of Bynes-related spotlight for himself, causing many to question his motives -- told Radar, "It's been a long few hours. I got police to be able to go to her home. I am told they found drugs and other things. I had proof she was suicidal."

"There were text messages and other things. I repeated all of this to the NYPD and they took it seriously," Jaxson continued. "I want the world to know that this is a victory and that she is now going to get the help she deserves."

He also tweeted about the ordeal (because of course he did):

And, being a publicist and all, he blogged about it, revealing why he chose social media for private conversations. You can read Jaxson's (rather self-congratulatory) blog post about the Bynes incidents here.

You may want to take it with a grain of salt, though. In about two weeks, he has a memoir somewhat ironically titled 'Do You Know Who I Am Yet?' hitting bookshelves.