SIS II, governed (in relation to the EAW) by Council Decision 2007/533/JHA on the establishment, operation and use of the second generation Schengen Information System (12th June 2007) (the “SIS II Decision”), is a centralised database in which EU Member States’ authorities enter data concerning persons wanted under an EAW (Article 26 SIS II Decision). Each Member State has authorities responsible for a national database (“N.SIS II”) and for sending any additional information via the system (the “SIRENE Bureau”). Border and police authorities are able to search the system directly. 
Alerts concerning a person wanted for surrender under an EAW are entered into SIS II together with data covering all the key fields of the EAW. This combination is treated as being the EAW itself (Article 31 SIS II Decision) and suffices for an arrest (and what we have referred to in section D as the Schengen Entry).
The SIS II Decision contains provisions on “flagging,” which enables an Executing State to require the Issuing State to add a flag to the alert prohibiting any arrest in the Executing State (Articles 24 and 25).
i. Before an arrest
Finding out if there is a SIS II alert
A person in any Member State can apply to find out whether there is currently a SIS II alert concerning them (Article 58 SIS II Decision). The provision of information is subject to any national rules that apply and the Issuing State’s opinion. Information will not be provided if it is “indispensable for the performance of a lawful task in connection with an alert or for the protection of the rights and freedoms of third parties” (Article 58(4) SIS II Decision).
You will need to identify the competent authority and the procedure in your Member State. Practice varies, and though some authorities will disclose the existence of an alert, others will not. The process may also take many months and the answers provided may be inconclusive.
You may also try to find out whether there are EAW and SIS II alerts issued by your or third Member States by checking for pending proceedings directly at the court, prosecution or police authorities or a given pending proceedings register, if that is permitted in the respective Member State. A lawyer in the Issuing State can help you with this task.
Having the SIS II alert flagged pre-emptively
If you are asked to represent someone who is aware of an EAW pending against them, and therefore that a SIS II alert is in place, it is possible for a flag to be added at the behest of a competent judicial authority where it is obvious that the EAW will have to be refused (Article 25 SIS II Decision). So, for instance, if you can demonstrate that one of the mandatory refusal grounds under Article 3 EAW FD applies, or that a fundamental right is at risk (see section E and section F) you could seek an order from a national court or authority (whichever is competent for these purposes in your Member State) ordering the SIS II / SIRENE Bureau to require that a flag be added to the alert by the Issuing State. This will prevent the person being arrested and EAW proceedings being started in your Member State. Of course, you will need to evaluate how strong such an application would be and the risk of inviting arrest upon the EAW by initiating such a challenge.
ii. After EAW proceedings
Ensuring that the SIS II alert is flagged in your Member State
If the Executing State judge refuses to surrender your client pursuant to the EAW, you should apply to the court to include in the decision an instruction to the Issuing State to add a SIS II flag, and ensure that the SIRENE Bureau requests that the flag be added. This will prevent further arrests in your Member State.
Dealing with the outstanding SIS II alert
If the EAW has been resisted by persuading the Issuing State to withdraw the underlying arrest warrant and EAW, the ISL should ensure that the issuing judicial authority also orders the withdrawal of the SIS II alert when it revokes the EAW. You should remind them to do this, since issuing authorities do not always do it automatically (see above section H.3.iii).
If the Executing State judge accepts your arguments and refuses to surrender the requested person, there is no obligation upon the Issuing State to remove the EAW and SIS II alert as a consequence. You must advise your client that they could face further arrests in other countries pursuant to the same EAW. In considering what, if any, action may be taken about the outstanding alert, you should ask an ISL whether there is any prospect of the EAW and underlying arrest warrant being challenged in light of your Member State’s refusal to surrender, particularly if it was established in the EAW proceedings that the ne bis in idem rule applies, or a fundamental right is at risk (see above section H.3. ii). If there was a refusal based on EU law grounds (for example, the Executing State considered that surrender should be refused on the basis of the ne bis in idem principle pursuant to Article 54 CISA and Article 3(2) EAW FD), the ISL should consider challenging the underlying warrant on this basis and, if necessary, seek a preliminary reference to the CJEU on the compatibility of the continuance of the EAW and SIS II Alert with EU law, and the Charter (see sections E.1 on ne bis in idem and E.3 on fundamental rights). However, we are not yet aware of a SIS II alert being challenged successfully after an EAW has been refused.
 Be aware that in older resources these are commonly referred to as ‘Article 95 alerts’ (a reference to the Convention Implementing the Schengen Agreement, which established the original Schengen Information System, which SIS II has replaced).
 National authorities are set out in The Schengen Information System: A guide for exercising the right of access (this concerns the system before SIS II but the authorities and practices are likely to be the same for SIS II).