Electronic Monitoring in Pre-Trial Detention: Section 173a StPO, House Arrest with Ankle Tag in Austria

Section 173a CCP bears the heading “House arrest” and was inserted into the CCP in 2010 by the Criminal Procedure Amendment Act (BGBl I 2010/64). It has been in force unchanged since 1 September 2010. Paragraph 1 of the section provides: “On application by the public prosecutor or the accused, pre-trial detention may be continued as house arrest, to be executed in the accommodation in which the accused has established a domestic residence.” The central provision of the section is set out in sentence 2 of para 1, it ties together four cumulative prerequisites, all of which must be satisfied at the same time.

First prerequisite, domestic residence. The accused must have accommodation in Austria in which house arrest can actually be executed. Under Section 66 of the Jurisdiction Act (JN), residence is the place at which the accused has settled with the intention of taking up permanent abode there; mere police registration is not sufficient (OGH 14 Nds 73/02). The accommodation must also be "suitable in light of the grounds for detention" (Explanatory Memorandum 772 BlgNR 24th legislative period, 9). Accommodation owned by a co-suspect, accommodation without stable mobile reception or accommodation that also houses several trial witnesses is regularly ruled out.

Second prerequisite, settled living conditions. Stability in housing, employment and social ties. The probation service (NEUSTART) reports to the court on these living conditions, agrees the concrete conditions of the house arrest with the accused and lays down the result in a social report for the detention hearing. Without this social report the court typically does not decide.

Third prerequisite, consent to electronic monitoring. The accused must formally consent to being monitored by suitable means of electronic supervision. Section 173a(1) CCP refers in technical terms to Section 156b(1) and (2) of the Execution of Sentences Act (StVG), the legislature points to that provision because the monitoring technology was first regulated in the field of executing sentences. Consent may be withdrawn at any time; a withdrawal leads, under Section 173a(4) sentence 1 CCP, to the mandatory termination of house arrest.

Fourth prerequisite, formal undertaking. At the detention hearing the accused expressly affirms that he or she will comply with the conditions agreed with the probation service. This undertaking is not merely formal, its breach is, under Section 173a(4) sentence 2 CCP, one of the classic grounds for revocation.

Two further substantive conditions are added to the first and second prerequisites: pre-trial detention must not be capable of being lifted through less intrusive measures under Section 173(5) CCP, while at the same time the purpose of detention under Section 182(1) CCP must remain attainable in this special form of execution. House arrest is therefore the second line: first the less intrusive measures are examined, then, if these are not sufficient, house arrest. House arrest is not a less intrusive measure within the meaning of Section 173(5) CCP, but a special form of executing the still-upheld pre-trial detention (so expressly OGH 12 Os 102/17t and 15 Os 165/10v; Kirchbacher/Rami in Fuchs/Ratz, WK StPO Section 173a, as at 1 January 2025, marginal no. 1). The heading of Section 173a and its para 1 first sentence use the term "house arrest", which the prevailing view regards as euphemistic; only the electronically monitored house arrest is permissible. Execution of pre-trial detention as house arrest without electronic monitoring is ruled out from the outset.

In practice, Kirchbacher/Rami note: "It is practically conceivable only in rare cases that the purposes of pre-trial detention can also be achieved through electronically monitored house arrest" (WK Section 173a marginal no. 4). Where a ground for detention exists and less intrusive measures do not suffice, the same risk can, as a rule, not be effectively countered by house arrest either. Roland Kier, in his handbook chapter, speaks of "particular reservations on the part of detention judges" towards this form of execution (Kier in Kier/Wess, HB Strafverteidigung Kap 9, as at 1 May 2022, marginal no. 9.65). From the defence perspective this means that the application must be especially carefully prepared in order to have any prospect of success.

The right to apply is noteworthy. Unlike the imposition of pre-trial detention, which under Section 173(1) CCP can only be ordered on the application of the public prosecutor, in the case of house arrest the accused is also entitled to apply. Such an application may, under Section 174(3) no. 8 CCP, be made at any time, not only at the mandatory first hearing. This makes the house arrest application a central defence instrument in pre-trial detention proceedings; counsel can initiate it without the participation of the public prosecutor. The application is decided by the detention and legal protection judge under Section 33(1) no. 1 CCP at a detention hearing that, under Section 176(1) no. 2 CCP, must be scheduled without delay (Section 173a(2) sentence 1 CCP).

The most important clarification at the outset: Section 173a CCP and Section 156b StVG are not the same. Both norms regulate an electronically monitored house arrest with an ankle tag, but they apply in entirely different phases of the proceedings, under different prerequisites and with different legal consequences.

Section 173a CCP is a particular form of executing pre-trial detention. It operates before the final conviction, in the investigation and main trial phase, and presupposes that pre-trial detention as such would be upheld (strong suspicion plus a ground for detention) but can be executed outside the prison. The accused remains legally in pre-trial detention; only the place of execution changes from the prison to the accused's own accommodation.

Section 156b StVG, by contrast, is a particular form of executing sentences. It applies only after a final conviction, the remaining sentence to be served may not exceed 24 months (for convictions under Sections 75, 76, 87, 107b(3a)(3), 143(2), 201, 202, 205, 205a, 206, 207, 207a, 207b and 278b-278g StGB the limit remains twelve months), and is granted in lieu of custodial execution as execution of the sentence in the convicted person's own accommodation. Under Section 156c StVG the convicted person contributes to the costs on an income-related basis (daily-rate scheme).

The Supreme Court expressly clarified this distinction in 2010: Austrian Supreme Court (OGH) 15 Os 165/10v of 23 December 2010 (legal proposition RS0126401). The OGH there formulated that house arrest under Section 173a CCP is “a particular form of executing pre-trial detention and not an alternative to pre-trial detention”. From this it follows that, for an order of house arrest, all prerequisites of pre-trial detention under Section 173 CCP must be present, in particular strong suspicion and a ground for detention under Section 173(2) CCP. Anyone applying for house arrest without attacking these prerequisites leaves the most important line of defence unused.

An important procedural consequence of the OGH decision concerns the fundamental-rights appeal: the continuation of pre-trial detention as house arrest may be challenged by a fundamental-rights appeal to the OGH under the Fundamental Rights Appeal Act (GRBG), because the electronically monitored house arrest is also a deprivation of liberty within the meaning of Article 5 ECHR. The rejection of the request to continue pre-trial detention as house arrest, by contrast, is not open to a fundamental-rights appeal (Section 1(2) GRBG; OGH 15 Os 165/10v; 12 Os 102/17t). Against the rejection of the house arrest application the ordinary route of the detention appeal under Sections 87 and 88 CCP to the Higher Regional Court is available. The period is, according to the prevailing view, 14 days from service of the written decision, which is delivered at the latest within 24 hours of pronouncement (Section 88(1) CCP; so expressly Kirchbacher/Rami in WK StPO Section 173a marginal no. 11). The shortened three-day period of Section 176(5) CCP does not apply here, because a decision on the application for electronically monitored house arrest is not a decision on the lifting or continuation of pre-trial detention within the meaning of Section 176(4) CCP (different view: Nimmervoll, Haftrecht³ 261).

Technically, Section 173a(1) CCP does refer to Section 156b(1) and (2) StVG, but that concerns only the means of monitoring (ankle tag, electronic supervision). The legal consequence remains different: in the case of Section 173a, pre-trial detention; in the case of Section 156b, execution of sentence. Anyone confusing the two risks applying the wrong norm and, with it, the wrong examination of the prerequisites.

Electronic monitoring in house arrest comprises three components, a transmitter on the body, a receiving unit in the accommodation and the prison's monitoring centre. Each component fulfils its own function and is coordinated with the others.

Transmitter on the body. An electronic ankle tag, a waterproof bracelet worn at the ankle, with a built-in radio transmitter and tamper sensor. The bracelet is designed so that any attempt to cut, open or remove it is immediately detected and reported to the monitoring centre. It is drip- and shower-proof and is deliberately not removed in everyday life.

Receiving unit in the accommodation. A stationary base station installed in the accused's home. It communicates via the mobile network with the prison's monitoring centre and reports the presence or absence of the transmitter within a defined radio zone. If the accused leaves this zone outside the permitted time windows, an alarm reaches the centre. Stability of mobile reception is therefore a technical suitability requirement for the accommodation, if reception is patchy, house arrest fails on the hardware alone.

GPS component. Some devices additionally provide a location function outside the radio zone, for example for the journey to the workplace or to medical treatment. Section 156b(1) StVG, to which Section 173a(1) CCP refers in technical terms, speaks generally of “suitable means of electronic supervision” without fixing the technology. The current state of the art therefore remains applicable; the concrete hardware and configuration are coordinated between the prison, NEUSTART and the accused.

The technical operation of the system is the responsibility of the prison. It sets up the hardware, maintains it, responds to alarms and, where there is reasonable suspicion, orders an inspection. The social support runs in parallel via NEUSTART, the probation service accompanies the accused during the house arrest, monitors compliance with the conditions and reports back as soon as problems become apparent.

Under Section 173a(3) CCP, the set-up follows a clearly regulated sequence: if the house arrest application is granted, the public prosecutor notifies the criminal police and the security authority of the place of residence. The prison sets up the technical means of electronic supervision. Only once the equipment is in place is the accused transferred from the prison to house arrest. A certain lead time can therefore elapse between the court's decision and the actual move into house arrest, counsel and relatives should be aware of this and factor it into expectation management.

House arrest is not release, it remains pre-trial detention, only in a more lenient form of execution. From this follows a clearly delineated catalogue of obligations, the breach of which under Section 173a(4) sentence 2 CCP counts among the classic grounds for revocation.

Duty to remain in the accommodation. In principle, the accommodation may not be left. Section 173a(2) last sentence CCP lists the permitted reasons for leaving exhaustively: reaching the workplace or place of training, procuring necessary daily necessities and obtaining necessary medical assistance, in each case by the shortest route. Other routes are not permissible: leisure activities, sport, visits to relatives, club meetings, restaurant visits, walks without a specific purpose. During the non-released times the accused is present in the accommodation.

Specification through the formal undertaking. Precisely which working or training hours are permissible, on which days daily necessities may be procured and which doctors may be consulted is governed by the individual agreement with the probation service. These conditions are recorded in the social report and the accused affirms them by formal undertaking at the detention hearing (Section 173a(2) sentence 2 last half-sentence CCP). From that moment the undertaking is binding, deviations trigger alarms in the monitoring centre.

Toleration of electronic monitoring. The accused wears the ankle tag continuously, accepts the radio monitoring in the accommodation and, where applicable, the GPS location on permitted routes. Any attempt to manipulate the transmitter triggers an alarm and counts as a breach. Leaving the accommodation outside the permitted times or routes is likewise detected immediately by the monitoring centre.

Cooperation with NEUSTART. Throughout the duration of the house arrest, the accused is obliged to maintain contact with NEUSTART, keep appointments, comply with reporting and cooperation duties, report changes in living circumstances (loss of employment, change of accommodation, new medical treatment). The probation service is therefore not merely the source of the prior report, but a continuing point of contact during the execution.

Maintenance of consent. Section 173a(1) last sub-clause CCP makes the accused's consent to electronic monitoring a constitutive prerequisite. This consent may be withdrawn at any time, Section 173a(4) sentence 1 CCP links to it the mandatory termination of the house arrest. A withdrawal of consent is therefore effective, but has a clear consequence: the accused is transferred back to the prison and pre-trial detention continues there as ordinary custodial detention.

Cost implications. Section 173a CCP makes no specific provision for the costs of electronic monitoring. In pre-trial detention house arrest the costs are borne by the prison, an income-related self-contribution as in the execution of sentence under Section 156c StVG is not provided for. This is a not unimportant difference from house arrest in the execution of sentences, where daily rates may apply. The time spent in house arrest is credited as pre-trial detention against any subsequently imposed custodial or pecuniary sentence under Section 38 StGB (so expressly Explanatory Memorandum 772 BlgNR 24th legislative period, 9). In the event of a final conviction to an unconditional custodial sentence, Section 173a(5) CCP applies, by analogy, Section 3(2) StVG: the convicted person is, for the purposes of ordering the execution of the sentence, "to be treated as if at liberty" and may, where appropriate, apply to serve the sentence as electronically monitored house arrest under Sections 156b ff StVG.

Consequences for detention hearings and detention orders. An important consequence of the order: from the start of execution as electronically monitored house arrest, the automatic detention hearings cease (Section 173a(1) last sentence CCP). The decision on the continuation or lifting of pre-trial detention may be issued in writing without a prior oral hearing. The remaining provisions on continuation, lifting and maximum duration of pre-trial detention continue to apply by analogy; in particular, the special acceleration principle in detention matters (Sections 9(2), 177(1) CCP) remains applicable and the maximum periods of Section 178 CCP (and, for juveniles, Section 35(3) JGG) apply unchanged.

Section 173a(4) CCP lists the grounds for revocation exhaustively. Anyone, whether relative or counsel, who wants to safeguard the house arrest should know them; every breach can lead to a return to custodial detention.

First ground: withdrawal of consent by the accused. Section 173a(4) sentence 1 CCP provides that, where the accused declares that he or she withdraws consent, the court is to revoke the house arrest and order the continued execution of pre-trial detention in the prison. The revocation takes place of the court's own motion, no application by the public prosecutor is required. In practice this rarely occurs, because the accused has typically fought for the house arrest and wants to keep it. Where it does happen, it is mostly for personal or family reasons that are no longer compatible with execution in the specific accommodation.

Second ground: breach of the formal undertaking. Section 173a(4) sentence 2 first half-sentence CCP provides that, on the application of the public prosecutor, the court revokes the house arrest where the accused, contrary to the undertaking, does not comply with the conditions. Classic configurations are unauthorised leaving of the accommodation outside permitted times or routes, frequenting prohibited places or persons, breach of abstinence requirements in the case of substance conditions, or contact with co-suspects or witnesses contrary to a contact ban fixed in the undertaking.

Third ground: purposes of detention no longer attainable. Section 173a(4) sentence 2 second half-sentence CCP forms the catch-all provision. It applies where, for external reasons, the purposes of detention under Section 182(1) CCP can no longer be attained in house arrest, for example through new collusion activity, manipulation of the ankle tag or new commission of offences during the execution. Loss of suitable accommodation (termination, loss of the home) and serious technical failure scenarios also fall under this provision. A revocation under sentence 2 requires an application by the public prosecutor.

Legal consequence of revocation. Section 173a(4) sentence 3 CCP provides that the transfer is to be entrusted to the criminal police. The accused is therefore brought back to the prison directly; pre-trial detention continues there as ordinary custodial detention. The time spent in house arrest so far counts as pre-trial detention time and is credited against the sentence in the event of a later conviction.

What relatives and counsel should take away from this: house arrest is winnable, but fragile. Every breach of the undertaking, even one that appears minor, can trigger revocation. Anyone living in house arrest should therefore, in case of doubt, interpret the conditions more restrictively than necessary and, in case of doubt, consult the probation service. In a conflict between a permitted route and a personal need, the narrower interpretation is safer than the broader one, the cost of revocation outweighs the personal convenience of a single errand.

From the experience of detention defence, three configurations can be identified in which the house arrest application has particularly good prospects, together with the typical refusal grounds that cause the application to fail.

Promising: pure risk of flight without foreign ties. The classic main case of Section 173a CCP. The accused has a settled domestic residence, an existing employment relationship and stable social ties locally. The asserted risk of flight is the only supporting assumption of pre-trial detention, it is defused directly by the ankle tag's binding to the accommodation, because every unauthorised movement is reported at once. In this configuration the house arrest application has the highest prospect of success.

Promising: white-collar cases with longer proceedings. File study, balance sheet and expert-report proceedings often stretch over months. White-collar cases are structurally favourable for Section 173a, the accused regularly has settled living conditions and a professional environment compatible with house arrest. The risk of collusion can be reduced through clear conditions, email and telephone restrictions, contact bans for co-suspects, separation from operational company management. Anyone presenting the court with a detailed package of conditions proactively neutralises the most common refusal ground.

Promising: care duties and child care. Where the accused is responsible for the care of minor children, the proportionality argument operates in favour of the more lenient form of execution. The logic: prolonged custodial detention affects not only the accused but also the children involved; house arrest allows the continuation of childcare and is therefore the milder means within the same execution goal. Section 156b(1) StVG recognises child care as equivalent to gainful occupation, that assessment carries over through the linking provision in Section 173a(1) CCP.

Arguments that convince at the detention hearing. Three points raise the success rate in practice: first, request the probation service's social report as early as possible, ideally before the detention hearing; Section 179 CCP allows provisional probation supervision in advance. Second, offer concrete conditions, workplace with fixed hours, medical treatment, addiction therapy where applicable. The more concrete, the more likely the court will follow. Third, document the technical suitability of the accommodation, mobile reception, adequate room layout, no co-suspects or aggrieved persons in the household.

Common refusal grounds. First: no suitable accommodation, no domestic residence, precarious housing, accommodation owned by a co-suspect. Second: risk of flight through foreign ties, multiple citizenships, family abroad, international business activity, only a short prior stay in Austria. Here the court typically assumes that the spatial binding to the accommodation does not sufficiently control the risk of flight, because the ankle tag only reports movement rather than physically preventing it. Third: risk of collusion through co-suspects in the household, family constellations, partners as co-suspects, trial witnesses in the immediate environment. Fourth: substance problems without stable therapeutic support, house arrest without a therapy link is regarded as too uncertain in prognosis.

Relationship with Section 173(5) CCP. A central rule of practice: before any house arrest application it must be examined whether pre-trial detention can be replaced at all by less intrusive measures under Section 173(5) CCP, formal undertaking to attend, passport deposit, residence condition, reporting duty, contact bans, abstinence requirements. Section 173a CCP is only the second line, where less intrusive measures are not sufficient but the purpose of detention remains attainable outside the prison. Anyone applying for house arrest without offering the less intrusive measures in parallel leaves the milder instrument unexamined, the court will regularly notice.

Link to the mandatory hearing under Section 174 CCP. In practice the house arrest application is announced as early as the first mandatory hearing or filed at the latest at the first detention hearing. Early filing is central, because the probation service needs several days of lead time to complete the social report. Anyone filing the application two weeks later loses valuable time, pre-trial detention continues in the prison in the meantime. More on the mandatory hearing in our article on strong suspicion.