What is the current state of the law when it comes to restricting the exercise of free speech on probation?

I agree with the majority's statement that ordinarily "line-drawing in probation matters is best left to the discretion of the sentencing judge," majority opinion at 568 supra, but our opinions make it clear that careful review is required of probation conditions that infringe on the lawful exercise of first amendment rights. As the court stated in United States v. Consuelo-Gonzalez, 521 F.2d 259, 265 (9th Cir. 1975) (en banc), although conditions infringing constitutional rights are certainly not presumed impermissible,