The principal question presented is whether the District Court improperly delegated its judicial authority to the United States Probation Office when it ordered as a special condition of supervised release that the defendant submit to mental health and substance abuse testing and evaluation and follow "any treatment recommendations." The defendant Allen M. Young ("Young") further argues that his sentence is procedurally unreasonable because: (1) the District Court erroneously applied the official victim enhancement of United States Sentencing Guidelines section 3A1.2(c)(1) ; and (2) the District Court failed to grant a downward departure pursuant to United States Sentencing Guidelines section 5K2.23. We conclude that the District Court did not improperly delegate its judicial authority and that the sentence is not procedurally unreasonable and therefore AFFIRM the October 11, 2016 judgment of the United States District Court for the Western District of New York (Frank P. Geraci, Jr., Judge ).
I. BACKGROUND
Young appeals from an October 11, 2016 judgment of the District Court convicting *668him, following a guilty plea, of possession with intent to distribute methylone in violation of 21 U.S.C. §§ 841(a)(1), 841(b)(1)(C), and 851. The District Court sentenced Young to 200 months' imprisonment to be followed by six years of supervised release, as well as a special assessment. On appeal, Young argues that the District Court erred by delegating to the Probation Office the decision of whether Young, upon release, would be required to participate in mental health or substance abuse treatment. He further argues that his sentence is procedurally unreasonable because: (1) the District Court erroneously applied the official victim enhancement of United States Sentencing Guidelines section 3A1.2(c)(1) ;1 and (2) the District Court failed to grant a downward departure pursuant to United States Sentencing Guidelines section 5K2.23.2
We review the imposition of conditions of supervised release for "abuse of discretion."3 We review legal issues arising from the imposition of such conditions de novo, and of course an error of law constitutes an abuse of discretion.4 When a defendant fails to object to a condition, we typically review for plain error, but we may "relax the otherwise rigorous standards of plain error review" under certain circumstances, such as where a defendant lacked prior notice of the challenged condition.5
The procedural reasonableness of a sentence is likewise reviewed for "abuse of discretion."6 A district court's interpretation of the Guidelines is reviewed de novo; its findings of fact are reviewed for clear error.7
II. DISCUSSION
A. Delegation to the Probation Office
1. Law
United States probation officers serve as "officers of the court."8 In their capacity as confidential advisers to the court, federal probation officers are regarded as "the court's eyes and ears, ... neutral information gatherer[ers] with loyalties *669to no one but the court."9 Indeed, because "the United States Probation Office is established pursuant to the direction of Congress as an arm of the United States District Court, it is reasonable to view the United States Probation Office itself as a legally constituted arm of the judicial branch."10 Although the Probation Office is undeniably part of the federal judiciary, we have nonetheless stated that there are limits on a District Court's ability to delegate judicial authority to a probation officer.
In determining whether the District Court impermissibly delegated its authority to the United States Probation Office when it imposed on Young special mental health and substance abuse conditions, we are guided by this Court's precedents in United States v. Peterson11 and United States v. Matta .12
In Peterson , we confronted the following special condition of probation: "[T]he defendant is to enroll, attend and participate in mental health intervention specifically designed for the treatment of sexual predators as directed by the U.S. Probation Office ."13 Our discussion focused principally on the ambiguity in the special condition's language. We noted that while the first clause ("[t]he defendant is to enroll, attend and participate") suggests that mental health treatment is mandatory, the second clause ("as directed by the U.S. Probation Office") could be understood to qualify the mandatory nature of that obligation.14 We vacated and remanded this aspect of the sentence so that, upon resentencing, the district court could resolve this ambiguity and clarify whether it intended mandatory therapy. As we explained, "[i]f the district court intends that the therapy be mandatory but leaves a variety of details, including the selection of a therapy provider and schedule to the probation officer, such a condition of probation may be imposed."15 If, however, "the court intends to leave the issue of the defendant's participation in therapy to the discretion of the probation officer, such a condition would constitute an impermissible delegation of judicial authority and should not be included."16 In sum, it was the district court's inclusion of the clause "as directed by the U.S. Probation Office" that rendered the otherwise mandatory special condition of counseling ambiguous and potentially unlawful.
In Matta , we addressed a special condition of supervised release which left "to the discretion of Probation" the decision of whether an inpatient or outpatient program was "most appropriate."17 We remanded, holding that "a district court may not delegate to the Probation Department decisionmaking authority which would make a defendant's liberty itself contingent on a probation officer's exercise of discretion."18 In sum, because inpatient treatment "affects a significant liberty interest," it cannot be imposed by a probation *670officer in his or her supervisory capacity, but must instead be "imposed by the district court and supported by particularized findings that it does not constitute a greater deprivation of liberty than reasonably necessary to accomplish the goals of sentencing."19
2. Analysis
On appeal, Young challenges the special conditions as recorded in the written judgment. The written judgment states the special conditions of supervised release as follows:
The defendant shall submit to substance abuse testing, to include urinalysis and other testing. Details of such testing to be approved by the U.S. Probation Office. If substance abuse is indicated by testing, the defendant is to complete a drug/alcohol evaluation and enter into any treatment as deemed necessary by the U.S. Probation Office and/or the Court. The defendant is not to leave treatment until discharge is agreed to by the U.S. Probation Office and/or the Court ....
The defendant is to submit to a mental health evaluation. If indicated by the evaluation, the defendant shall participate in mental health treatment, the details of such treatment to be approved by the U.S. Probation Office . The defendant is not to leave such treatment until discharge is agreed to by the U.S. Probation Office and the treating agency ....20
Pointing to the text emphasized above, Young argues that the special conditions unlawfully delegate judicial authority to the Probation Office.
Importantly, the decretal text Young complains of appears only in the written judgment. By contrast, during the sentencing hearing, the District Court orally pronounced the special conditions as follows:
You must submit to drug testing and evaluation and follow any treatment recommendations.
You also must submit to mental health testing, evaluation, and any treatment recommendations.21
Insofar as there is a variance between the written and oral conditions, the District Court's oral pronouncement controls.22 Later written modifications of the terms of supervised release omitted from the oral pronouncement are permitted where they add: (1) conditions of supervised release listed as "mandatory" or "standard" in subsections 5D1.3(a) or (c) of the United States Sentencing Guidelines; (2) conditions "recommended" by subsection 5D1.3(d) of the Guidelines;23 and (3)
*671"basic administrative requirements that are necessary to supervised release."24
a. Substance Abuse Condition
The first written condition-the "Substance Abuse Condition"-appears to suffer from precisely the same defect as the condition found objectionable in Peterson . Whereas the first clause ("defendant is to complete a drug/alcohol evaluation and enter into any treatment") suggests that substance abuse treatment is mandatory, the second clause ("as deemed necessary by the U.S. Probation Office") can be understood to delegate authority to the Probation Office. As in Peterson , it is unclear from this written condition whether the District Court is mandating treatment if indicated by evaluation, or leaving the ultimate decision of whether to require treatment to the Probation Office.
By contrast, the District Court's oral pronouncement of the Substance Abuse Condition-which controls-unambiguously requires Young to enroll in substance abuse treatment if indicated by testing. Unlike Peterson , the oral Substance Abuse Condition does not contain a subordinate clause that renders ambiguous an otherwise mandatory obligation. Rather, insofar as evaluation indicates a need for treatment, the treatment is mandatory pursuant to the oral pronouncement; it does not constitute an improper delegation of judicial authority. The remainder of the written Substance Abuse Condition is fully consistent with both the oral instructions of the District Court as a "basic administrative requirement."25 It stands and properly authorizes the Probation Office to supervise and oversee that treatment.
In light of Matta , however, we construe this authorization to exclude the imposition of inpatient treatment.26 Under Matta, the imposition of inpatient treatment must be "supported by particularized findings that it does not constitute a greater deprivation of liberty than reasonably necessary to accomplish the goals of sentencing."27 The Court made no such findings here. We also construe this authorization to apply to the entirety of Young's term of supervised release.
b. Mental Health Condition
Unlike the written Substance Abuse Condition, the written "Mental Health Condition" constitutes an unambiguously lawful, and indeed advisable, means of delegating supervisory authority to the Probation Office. The written Mental Health Condition-"If indicated by the evaluation, the defendant shall participate in mental health treatment ...."28 -clearly and unambiguously orders Young's participation in mental health treatment. It leaves to the Probation Office's discretion *672only the approval of "details of such treatment,"29 which is clearly permissible under Peterson .30
The oral "Mental Health Condition" is no different; it similarly mandates treatment for Young if treatment is indicated by a mental health evaluation. As with the Substance Abuse Condition, we construe the Mental Health Condition to exclude inpatient treatment, since such "restrictive" programs must be supported by particularized findings.31 We also construe the District Court's authorization to apply to the entirety of Young's term of supervised release.32
B. Procedural Reasonableness of Young's Sentence
1. Official Victim Enhancement
Young argues that his sentence is procedurally unreasonable because the District Court erroneously applied the official victim enhancement of United States Sentencing Guidelines section 3A1.2(c)(1). Young appears to argue that he did not "assault" law enforcement officers within the meaning of section 3A1.2(c)(1) because he did not intend to hit the officers with his car or to cause them fear and did not realize that the individuals toward whom he drove his vehicle were police officers.
The official victim enhancement of Guidelines section 3A1.2(c)(1) provides as follows:
If, in a manner creating a substantial risk of serious bodily injury, the defendant ... knowing or having reasonable cause to believe that a person was a law enforcement officer, assaulted such officer during the course of the offense or immediate flight therefrom ... increase by 6 levels.33
We have already held, in a somewhat different context, that the word "assault" refers to the common-law offense of assault.34 "[C]ommon-law assault consisted of either attempted battery or the deliberate infliction upon another of a reasonable fear of physical injury ...."35
*673In applying this Guidelines provision during the sentencing hearing, the District Court stated as follows:
Sentencing Guideline 3A1.2(c) indicates that there should be a six level increase to the offense level if the defendant acted in a manner creating a substantial risk of serious bodily injury knowing or having reasonable cause to believe that a person was a law enforcement officer during the course of the offense or the immediate flight therefrom.
Again, based upon the evidence that the Court found credible at the hearing, the Court finds that there was more than sufficient evidence, clearly more than a preponderance of the evidence that the defendant created a substantial risk of serious bodily injury to the officers who were attempting to execute the search warrant on this occasion on him and on his motor vehicle on December 13th, 2012.
That he created a substantial risk of serious injury to the officers when he initially reversed his vehicle at a high speed while the officers were beside the vehicle, more importantly, when he drove his vehicle directly at one of the officers.
The Court finds that the defendant's argument that he did not know that the individuals involved were police officers ... is not credible or logical based upon the evidence in this case, including evidence that the two officers were wearing badges around their neck as they approached him and yelled multiple times in loud voices please stop.36
Therefore, the Court finds the evidence is really quite overwhelming regarding the defendant's action in creating a substantial risk of serious bodily injury to these officers and, therefore, the six level increase pursuant to Guideline Section 3A1.2(c) shall be applied.37
We conclude that this record is sufficient to sustain the District Court's application of the official victim enhancement. The record supports the District Court's finding by a preponderance of the evidence that Young knew or had reasonable cause to know that the individuals involved were law enforcement officials. Moreover, the District Court's findings adequately support a conclusion that Young committed an assault by driving his car directly at one of the officers.38 Accordingly, the District Court did not err by applying section 3A1.2(c) to Young.
2. Section 5K2.23 Downward Departure
Young also argues that his sentence is procedurally unreasonable because the District Court failed to grant a downward departure to account for the time he spent in presentence state custody before his federal conviction. Young's main theory in support of this argument is that the District Court improperly failed to apply United States Guidelines section 5K2.23.
Because Young failed to raise this objection before the District Court, we review *674the procedural reasonableness of his sentence for plain error.39
Guidelines section 5K2.23 ("Discharged Terms of Imprisonment (Policy Statement)") provides in relevant part:
A downward departure may be appropriate if the defendant (1) has completed serving a term of imprisonment; and (2) subsection (b) of § 5G1.3 ... would have provided an adjustment had that completed term of imprisonment been undischarged at the time of sentencing for the instant offense.40
We conclude that Young's sentence is not procedurally unreasonable, because Young did not qualify for a downward departure under section 5K2.23. Section 5K2.23 incorporates the terms of Guidelines section 5G1.3(b).41 Guidelines section 5G1.3(b), for its part, can apply only if "a term of imprisonment resulted from another offense that is relevant conduct to the instant offense of conviction."42 Young had been held in custody on related New York state charges, but he himself concedes that he was never sentenced to prison for the conduct charged in New York state court.43 Since Young never received a "term of imprisonment," he has not satisfied the second condition of Guidelines section 5K2.23 ; therefore, section 5K2.23 cannot have applied to Young's case. Accordingly, the District Court's failure to consider section 5K2.23 when determining Young's sentence does not qualify as error, much less plain error.44
*675III. CONCLUSION
In summary, we hold that the District Court did not improperly delegate to the United States Probation Office the decision of whether Young would be required to undergo treatment. A district court may mandate, in advance of testing and evaluation, any necessary or recommended outpatient treatment, and may authorize the Probation Office to approve and oversee the details of such treatment. This authorization lasts for the entirety of the defendant's term of supervised release. To mandate inpatient treatment, a district court must make particularized findings that such a course of treatment does not constitute a greater deprivation of liberty than reasonably necessary to accomplish the goals of sentencing. We further hold that Young's sentence is not procedurally unreasonable.
We therefore AFFIRM the District Court's judgment of October 11, 2016.
I fully concur in the Court's opinion insofar as it holds that Young's sentence was procedurally reasonable. I respectfully dissent from that portion of the opinion that upholds the challenged conditions of supervised release, because I believe that the conditions, as they appear both in the written judgment and in the oral pronouncement of sentence, are inconsistent with United States v. Peterson , 248 F.3d 79 (2d Cir. 2001), and United States v. Matta , 777 F.3d 116 (2d Cir. 2015), in which we found that similar conditions improperly delegated the Court's authority to the Probation Office. I do not disagree with the Court's explanation of the governing principle. My disagreement is with its characterization of the conditions imposed in this case.
The Court construes the oral Substance Abuse Condition as "mandatory" because it "does not contain a subordinate clause that renders ambiguous an otherwise mandatory obligation." Maj. Op. 671. The condition is indeed "mandatory" in that it uses mandatory language to the defendant ("You must ..."). But with respect to treatment, what Young is mandated to do is whatever the Probation Officer (or perhaps someone other than the Probation Officer) decides should be done: "You must submit to drug testing and evaluation and follow any treatment recommendations ." Appellant App'x 65 (emphasis added). Unlike the Court in Matta , the district court did not decide that drug treatment of any kind was necessary, nor did it require that Young participate in such treatment. The obligation is conditional: Young must participate in drug treatment only if enrollment in a drug treatment program is "recommend[ed]" by whoever performs the "testing and evaluation." Id. The condition imposed does not even require Young to obtain treatment if he fails a urine test for an illicit substance; if it did that, it could be argued that the judge had imposed drug treatment whenever a putatively objective test result showed drug use, leaving the Probation Officer in that case with only the ministerial task of arranging for (non-residential) drug treatment. Instead, participation in drug treatment is required only upon a "recommendation," based on a subjective "evaluation" of whether a positive test result - presumably along with other evidence relevant to whether the failure was a one-time lapse or indicative of a continuing problem requiring treatment *676- indicates to the evaluator (perhaps the Probation Officer, perhaps some independent medical or drug treatment agency subcontracted to perform the "evaluation") that such treatment is indicated.1
The Mental Health Condition is similarly structured. It too (in its oral version) requires Young to "submit to mental health testing, evaluation, and any treatment recommendations." Id. This condition thus plainly requires mental health treatment (as construed by the majority, limited to outpatient treatment) only if such treatment is recommended by whoever performs the evaluation .2 The Mental Health Condition is, if anything, even clearer than the Drug Treatment Condition in delegating the determination of whether such treatment is appropriate not merely to the Probation Officer (who presumably is not a trained or licensed mental health practitioner), but to a psychiatrist, psychologist, or other mental health professional who would be tasked with evaluating the defendant and determining whether he requires treatment. I do not see how this can be construed as a determination by the district court that Young is mandated to submit to mental health treatment as a condition of his release. It requires such treatment only at the discretion of someone other than the judge.
I do not suggest that the ruling of the Court impinges in some deeply unacceptable way on the responsibilities of the courts or the rights of defendants. Young is sentenced to 200 months of imprisonment. To require a district court to decide today whether he will require drug or mental health treatment more than 15 years into the future would make little sense. And it is arguably cumbersome (but perhaps not too much so, given the significance of the potential imposition on the defendant) to require the Probation Office to return to the court if it believes, on the basis of mandated drug or mental health testing after his release, to ask the district court to modify the conditions of release to require treatment. So a system that would permit broader delegation to the Probation Office than is permitted by our precedents would certainly be defensible. For good or ill, however, our precedents do not permit such a practice.
Because the conditions imposed here can only be read as subjecting the defendant to drug and mental health treatment if the Probation Office (or some other professional) determines that such treatment is necessary, I respectfully dissent.