In 2008 the Government launched its family drug policy strategy, which aimed to prevent intergenerational harm as a consequence of parental substance misuse (HM Government, 2008) and to improve outcomes for children affected by parental substance misuse (Harwin and Ryan, 2008). The first UK FDAC was set up in London in 2008 as a three-year pilot funded by central government in the Central London Family Proceedings Court. The London FDAC was followed by sites in Milton Keynes and Buckinghamshire (2014) and East Sussex (2015). FDACs aim to improve outcomes for children and families by providing an alternative way of working with parents’ experience alcohol or substance misuse involved in care proceedings. The primary aim of FDAC is to ensure that parents are reunified with their child at the end of care proceedings if it is safe to do so. If reunification is not possible, then the aim is to find an alternative carer for the child swiftly, to give the child the best chance for permanency and stability. FDACs use a ‘problem-solving’ court approach to justice, whereby courts use their authority to help address the complex social issues that bring people before them (Harwin and Ryan, 2008; Roberts et al., 2017). FDACs encourage parents to believe recovery and change are possible, along with aiming to provide a realistic understanding of the challenges they face. Specialist, designated judges provide parents with regular supervision and support through fortnightly court reviews. A specialist multi-disciplinary team also works closely with the courts and parents to support families to change and overcome their substance misuse problems and other difficulties. Children and Families Act 2014 The Children and Families Act 2014 made several substantive changes to the implementation of care proceedings. The changes most relevant to FDAC include the use of experts in care proceedings and the introduction of new limits on the duration of care proceedings. S13 restricted the use of experts as these delayed cases. S14 introduced a 26-week limit on the length of care proceedings, though extensions can be granted in some circumstances. The National Unit The Department of Education’s (DfE) Children’s Social Care Innovation Programme to create the FDAC ‘National Unit’ to scale-up the intervention. The National Unit supported nine FDAC sites and closed in September 2018. Further information about the National Units implementation was explored in Roberts et al. (2017). Effectiveness Early evidence about FDAC was promising. Harwin et al. (2011) found that FDAC parents were more likely to stop using substances, and more likely to be reunified with their children relative to a comparison group. This study also provided some evidence that FDAC could provide cost savings by using fewer experts relative to ‘business-as-usual’ care proceedings. A study of the London FDAC found that a higher proportion of parents whose case was heard in FDAC had ceased misusing substances by the end of proceedings, and more FDAC than comparison families were reunited with their children. Additionally, proportionately fewer children in FDAC families experienced new neglect or abuse in the first year following reunification (Harwin et al., 2014). The ‘After FDAC: outcomes 5 years later’ study, funded by the Innovation Programme, estimated that a higher proportion of FDAC than comparison reunification mothers abstained from drugs or alcohol over the five-year follow-up (Harwin et al., 2016; Harwin et al. 2018). It also found that a significantly higher proportion of FDAC than comparison mothers who had been reunited with their children at the end of proceedings were estimated to experience no disruption to family stability at 3-year follow-up. Variation between sites FDACs also deliver their support differently across sites. All sites deliver support during care proceedings, but some sites also offer pre-proceedings or post-proceedings support (such as Gloucestershire). Some sites offer peer-mentoring, and overall staffing varies between sites. Additionally, some teams are embedded within Local Authorities (such as Gloucestershire) whilst other FDAC teams stand alone (such as London). Variation also exists between sites when there is subjective decision making (such as deciding which cases to offer support to out of a sample of cases that meet the inclusion criteria). Currently there is limited evidence about the extent of this variation. Rationale for further evaluation of FDAC Prior evidence suggests that FDAC is a promising intervention for children in families with alcohol or substance misuse. Yet much of the prior evidence about FDAC’s effectiveness comes from the London FDAC site. Furthermore, these evaluations assessed the effectiveness of FDAC before the reforms introduced by the Children and Families Act 2014, which changed how care proceedings are administered. A separate feasibility study was therefore carried out to establish a research design to evaluate the impact of FDAC on outcomes for children and families across FDAC sites and in light of legislative reform. The design of the current study is the result of this feasibility study. Evaluation The impact evaluation will use data collected by FDAC sites and administrative data from Local Authorities in Coarsened Exact Matching (CEM). CEM is a quasi-experimental approach that can be used to mitigate selection bias when selection is driven by observed characteristics. The primary outcome of the study is reunification of children with their parents at the end of care proceedings. Secondary outcomes are parental drug and alcohol use cessation, whether the final care-proceedings hearing is contested and whether expert witnesses have been used in care proceedings. The implementation and process evaluation will unpack how the programme is implemented by conducting case studies in six of the fifteen FDAC sites in England.