Jax Taylor's Lawyer Claims Brittany Cartwright Is Trying to 'Beat Him Down' in Custody Fight

Jax Taylor's lawyer claims Brittany Cartwright is trying to "beat him down" through their custody and restraining order battles ... and believes Brittany hopes the pressure will cause him to stray from his sobriety.

Jax's attorney Mark Vincent Kaplan tells TMZ ... Brittany attempted to limit Jax's custody as part of her restraining order request, but the court denied all her requests. He says it's notable Brittany did not seek to limit Jax's custody at any point during the past year, and claims her current concerns are based on fabricated emergencies rather than facts.

The lawyer says Brittany knew the two sides were going to court based on communications between their attorneys ... and claims that's why she rushed to file what he calls a fabricated emergency.

Kaplan says Jax has passed every drug test since leaving rehab and claims Brittany is trying to "beat him down" in hopes he will "stray from his maintained sobriety." He adds ... "that is a goal for which she will not succeed."

As TMZ first reported ... Jax filed for a restraining order against Brittany, asking a judge to order her to stay 100 yards away from him and not contact him. He also asked the court to stop her from interfering with his business deals.

Jax claimed Brittany had targeted multiple employers and partners, costing him a $175K role on Fox's "Special Forces." He also accused her of calling him "asshole," "loser" and "dirty dick."

Jax has said he's been sober for nearly two years, attends weekly therapy and voluntarily submits to random drug testing.

We reached out to Brittany's reps ... so far, no word back.